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C-IN2 New York Core Signature black Y-back thong front view
C-IN2 New York Core Signature Y-Back Thong in black, rear view
C-IN2 New York Core Signature black Y-back thong underwear viewed from the rear
C-IN2 New York Core Signature black Y-back thong underwear front view
C-IN2 New York Core Signature black Y-back thong with minimalist rear straps
C-IN2 New York Core Signature black Y-back thong front view
C-IN2 New York Core Signature Y-Back Thong in black, rear view
C-IN2 New York Core Signature black Y-back thong underwear viewed from the rear
C-IN2 New York Core Signature black Y-back thong underwear front view
C-IN2 New York Core Signature black Y-back thong with minimalist rear straps

Product Details

One strap, zero lines — Y not?

The Y-back takes the thong one step further: a single elastic strap down the back, a sculpted pouch up front, and 100% cotton everywhere it touches. Barely there, completely comfortable — and nothing shows under anything.

Fabric
100% Cotton. Soft, breathable, and natural against the skin — the broken-in feel of a favorite tee, from the first wear.

Fit & Silhouette
Men's low-rise cotton Y-back thong — sits below the natural waist with a signature Y-back elastic strap and minimal coverage.

Contour Pouch
Sculpted 1-ply contour pouch with center-seam construction — light lift and natural shape, right where you want eyes to land.

Leg Openings
Clean elastic binding sits flat against the skin — no digging, nothing to adjust.

Waistband
1.5" exposed elastic waistband with the new signature C-IN2 logo in repeat.

Fit note
True to size. For a looser fit, go one size up.

Care
Machine wash.
Imported.

Core

C-IN2's foundation — every essential silhouette, cut in soft, breathable 100% cotton that feels better the longer you own it. The drawer you build once and reach for every day.

New

Core Signature Y-Back Thong Black

by C-IN2 New York
$26
No reviews yet
Our philanthropic promise $1.82
How the number works
The part of this price that goes to work. A fixed amount from this sale is set aside into the Dark Yarn philanthropy fund and allocated publicly at every milestone. It was calculated when the price was set, and it doesn't change after you buy. How it works
New with tags · Authentic
Every designer piece comes new with tags, from one reputable luxury supplier or direct from the independent brand. We don't buy from marketplaces or individuals. Never secondhand.
A real person answers
Questions on fit, fabric or sizing: a reply within 24 hours, from a person. If something's wrong, we fix it before we explain it. Ask us
Returns
30 days, unworn, and we pay the return shipping. Final-sale pieces are marked and can't be returned. Holiday orders can be returned through January 15.
Size Guides

Size Guide

Pick a category, find your usual size in the first column, then read across for the same size in other countries. Each table starts with body measurements so you can size from a tape measure. Where a product uses the brand's own scale, the label on that product page takes priority.

How to measure

Use a soft tape over light clothing. Keep it level and snug, not tight. Between sizes? Take the larger for outerwear, the smaller for close-fitting knits and swim.

Measurement How to take it
Chest / Bust Around the fullest part of the chest, tape under the arms and across the shoulder blades
Waist Around the natural waist, the narrowest point above the hip bones
Hips Around the fullest part of the hips and seat, feet together
Inseam From the top of the inner thigh to the ankle bone, standing straight
Foot length Stand on paper, heel to a wall, mark the longest toe; measure heel to mark. Use the longer foot
Head Around the head where a hat sits, about 1 cm (½ in) above the ears and eyebrows
Hand Around the palm at the knuckles, excluding the thumb, dominant hand
Finger Wrap paper around the finger, mark the overlap, measure in mm; or the inside diameter of a ring that fits

Measure feet and fingers at the end of the day, when they are largest.

Women's clothing

Tops, dresses, knitwear and outerwear. Size by bust.

Swipe sideways to see every column →

Size Bust in Bust cm Waist in Waist cm Hips in Hips cm US UK/AU EU/FR IT DE JP
XXS 31.5 80 24 61 34 86 0 4 32 36 30 5
XS 32.5 83 25 64 35 89 2 6 34 38 32 7
S 33.5 85 26 66 36 91 4 8 36 40 34 9
S 34.5 88 27 69 37 94 6 10 38 42 36 11
M 35.5 90 28 71 38 97 8 12 40 44 38 13
M 36.5 93 29 74 39 99 10 14 42 46 40 15
L 38 97 30.5 77 40.5 103 12 16 44 48 42 17
L 39.5 100 32 81 42 107 14 18 46 50 44 19
XL 41 104 33.5 85 43.5 110 16 20 48 52 46 21
XXL 43 109 35.5 90 45.5 116 18 22 50 54 48 23

Italian sizes run two numbers above French: a French 38 is an Italian 42. Japanese sizes run small; when in doubt go up one.

Women's bottoms, underwear & swim

Pants, shorts & skirts

Swipe sideways to see every column →

Size Waist in Waist cm Hips in Hips cm US UK/AU EU/FR IT Jeans
XXS 24 61 34 86 0 4 32 36 24
XS 25 64 35 89 2 6 34 38 25
S 26 66 36 91 4 8 36 40 26
S 27 69 37 94 6 10 38 42 27
M 28 71 38 97 8 12 40 44 28
M 29 74 39 99 10 14 42 46 29
L 30.5 77 40.5 103 12 16 44 48 30
L 32 81 42 107 14 18 46 50 32
XL 33.5 85 43.5 110 16 20 48 52 33
XXL 35.5 90 45.5 116 18 22 50 54 35

Underwear, bikinis & one-pieces

Swipe sideways to see every column →

Size Hips in Hips cm US dress UK/AU EU/FR IT Panty (US)
XS 34–35 86–89 0–2 4–6 32–34 36–38 5
S 36–37 91–94 4–6 8–10 36–38 40–42 6
M 38–39 97–99 8–10 12–14 40–42 44–46 7
L 40.5–42 103–107 12–14 16–18 44–46 48–50 8
XL 43.5–45.5 110–116 16–18 20–22 48–50 52–54 9

Bikini tops with cup sizes use bra sizing: band is underbust in inches rounded to the nearest even number; cup is bust minus band (1 in = A, 2 = B, 3 = C, 4 = D).

Men's clothing

T-shirts, shirts, knitwear, hoodies and jackets. Size by chest.

Swipe sideways to see every column →

Size Chest in Chest cm Waist in Waist cm Neck in Neck cm US/UK/AU EU/IT/FR DE JP
XS 34–36 86–91 28–30 71–76 14–14.5 36–37 XS 44 44 S
S 36–38 91–97 30–32 76–81 15–15.5 38–39 S 46 46 M
M 38–40 97–102 32–34 81–86 15.5–16 39–41 M 48 48 L
L 40–42 102–107 34–36 86–91 16.5–17 42–43 L 50 50 LL
XL 42–44 107–112 36–38 91–97 17.5–18 44–46 XL 52 52 3L
XXL 44–46 112–117 38–40 97–102 18.5–19 47–48 XXL 54 54 4L
3XL 46–48 117–122 40–42 102–107 19–19.5 48–50 3XL 56 56 5L

Italian designer pieces are often labelled by EU number only (46, 48, 50). Japanese letter sizes run one size smaller than US.

Men's bottoms, underwear & swim

Pants, shorts & joggers

Swipe sideways to see every column →

Size Waist in Waist cm Hips in Hips cm US/UK/AU EU/IT/FR DE JP
XS 28 71 34–35 86–89 28 44 44 73
S 30 76 36–37 91–94 30 46 46 76
M 32 81 38–39 97–99 32 48 48 82
M 33 84 39–40 99–102 33 49 49 85
L 34 86 40–41 102–104 34 50 50 88
L 36 91 42–43 107–109 36 52 52 91
XL 38 97 44–45 112–114 38 54 54 97
XXL 40 102 46–47 117–119 40 56 56 102
3XL 42 107 48–49 122–124 42 58 58 107

Inseam: short 30 in (76 cm), regular 32 in (81 cm), long 34 in (86 cm).

Underwear, swim briefs, trunks & swim shorts

Swipe sideways to see every column →

Size Waist in Waist cm US/UK EU IT FR JP
XS 26–28 66–71 XS 3 2 1 S
S 28–30 71–76 S 4 3 2 M
M 30–33 76–84 M 5 4 3 L
L 33–36 84–91 L 6 5 4 LL
XL 36–39 91–99 XL 7 6 5 3L
XXL 39–42 99–107 XXL 8 7 6 4L

Briefs, thongs, jocks and swim tangas are cut to fit snugly; stay with your measured size.

Women's shoes

Size by foot length; the chart allows about 1 cm (⅜ in) beyond the toe.

Swipe sideways to see every column →

Foot in Foot cm US UK EU IT JP cm AU
8.5 21.6 5 3 35.5 35 22 5
8.7 22.0 5.5 3.5 36 35.5 22.5 5.5
8.9 22.5 6 4 36.5 36 23 6
9.0 22.9 6.5 4.5 37 36.5 23.5 6.5
9.25 23.5 7 5 37.5 37 24 7
9.4 23.9 7.5 5.5 38 37.5 24.5 7.5
9.6 24.4 8 6 38.5 38 25 8
9.75 24.8 8.5 6.5 39 38.5 25.5 8.5
9.9 25.2 9 7 39.5 39 26 9
10.1 25.7 9.5 7.5 40 39.5 26.5 9.5
10.25 26.0 10 8 40.5 40 27 10
10.4 26.4 10.5 8.5 41 40.5 27.5 10.5
10.6 26.9 11 9 41.5 41 28 11
10.75 27.3 11.5 9.5 42 41.5 28.5 11.5
10.9 27.8 12 10 42.5 42 29 12

Italian-made shoes often run a half size small against the EU standard; use the IT column for Italian brands. Width: standard B / medium, wide D / W.

Men's shoes

Size by foot length; the chart allows about 1 cm (⅜ in) beyond the toe.

Swipe sideways to see every column →

Foot in Foot cm US UK EU IT JP cm AU
9.25 23.5 6 5 39 38.5 24 5
9.4 23.9 6.5 5.5 39.5 39 24.5 5.5
9.6 24.4 7 6 40 39.5 25 6
9.75 24.8 7.5 6.5 40.5 40 25.5 6.5
9.9 25.2 8 7 41 40.5 26 7
10.1 25.7 8.5 7.5 42 41 26.5 7.5
10.25 26.0 9 8 42.5 41.5 27 8
10.4 26.4 9.5 8.5 43 42 27.5 8.5
10.6 26.9 10 9 43.5 42.5 28 9
10.75 27.3 10.5 9.5 44 43 28.5 9.5
10.9 27.8 11 10 44.5 43.5 29 10
11.1 28.2 11.5 10.5 45 44 29.5 10.5
11.25 28.6 12 11 46 44.5 30 11
11.4 29.0 12.5 11.5 46.5 45 30.5 11.5
11.6 29.4 13 12 47 45.5 31 12
11.9 30.2 14 13 48.5 46.5 32 13

UK and Australian men's sizes are one number below US. Width: standard D / medium, wide EE / W.

Accessories

Hats & headwear

Swipe sideways to see every column →

Size Head in Head cm Fitted (US) UK
XS 20.5–21 52–53 6½ – 6⅝ 6⅜ – 6½
S 21.25–21.75 54–55 6¾ – 6⅞ 6⅝ – 6¾
M 22–22.5 56–57 7 – 7⅛ 6⅞ – 7
L 22.75–23.25 58–59 7¼ – 7⅜ 7⅛ – 7¼
XL 23.5–24 60–61 7½ – 7⅝ 7⅜ – 7½
XXL 24.5–25 62–63 7¾ – 7⅞ 7⅝ – 7¾

Snapbacks and adjustable caps fit S through L in one size.

Belts

Choose a belt two inches (5 cm) above your pant waist so it buckles on the middle hole.

Swipe sideways to see every column →

Pant waist in Belt in Belt cm Size
28 30 75 XS
30 32 80 S
32 34 85 S / M
34 36 90 M
36 38 95 L
38 40 100 L / XL
40 42 105 XL
42 44 110 XXL

Gloves & mittens

Swipe sideways to see every column →

Size Hand in Hand cm Men's Women's
XS 6–6.5 15–16.5 – 6
S 6.5–7 16.5–18 7 6.5
M 7–7.5 18–19 7.5 7
M / L 7.5–8 19–20.5 8 7.5
L 8–8.5 20.5–21.5 8.5 8
XL 8.5–9 21.5–23 9 –
XXL 9–9.5 23–24 9.5 –

Socks

Swipe sideways to see every column →

Size Men's US shoe Women's US shoe EU shoe
S 3–6 4–7 35–38
M 6–9 7–10 39–42
L 9–12 10–13 43–46
XL 12–15 – 47–50

Rings

Measure the inside diameter of a ring that fits, or your finger's circumference in mm. Knuckle size matters more than the base of the finger.

Swipe sideways to see every column →

Diameter mm Circ. mm US/CA UK/AU EU/ISO FR / IT JP
14.9 46.8 4 H 47 7 7
15.3 48.0 4.5 I 48 8 8
15.7 49.3 5 J½ 49 9 9
16.1 50.6 5.5 K½ 51 10.5 10
16.5 51.9 6 L½ 52 12 11
16.9 53.1 6.5 M½ 53 13 12
17.3 54.4 7 N½ 54 14.5 14
17.7 55.7 7.5 O½ 56 15.5 15
18.1 57.0 8 P½ 57 17 16
18.5 58.3 8.5 Q½ 58 18 17
18.9 59.5 9 R½ 59 19.5 18
19.4 60.8 9.5 S½ 61 21 19
19.8 62.1 10 T½ 62 22 20
20.2 63.4 10.5 U½ 63 23.5 22
20.6 64.6 11 V½ 65 24.5 23
21.0 65.9 11.5 W½ 66 26 24
21.4 67.2 12 X½ 67 27 25
21.8 68.5 12.5 Z 68 28.5 26
22.2 69.7 13 Z½ 70 29.5 27

Bags, wallets, scarves, sunglasses and other jewelry are one size; dimensions are on each product page.

Quick rules & fit notes
From To Rule
US women's dress UK / AU Add 4
US women's dress EU / FR Add 32
US women's dress IT Add 36
FR IT Add 4
US men's chest (in) EU / IT Add 10
US men's waist (in) EU / IT Add 16
US men's shoe UK Subtract 1
US women's shoe UK Subtract 2
US men's shoe EU Add 33
US women's shoe EU Add 31
Any shoe JP Foot length in cm
Pant waist (in) Belt (in) Add 2

Fit by product type

Product Fit If between sizes
Outerwear, hoodies, sweatshirts Relaxed, room for a layer Size up
T-shirts, tanks, polos True to size Stay
Performance & activewear Close to the body Size down
Underwear, briefs, swim Snug Stay
Dresses, skirts True to size Size by the larger of bust or hips
Jeans True to size; stretch relaxes with wear Size down for stretch denim
Shoes True to size Up for a thick sock, down for a narrow foot

Unisex and lifestyle pieces are cut to men's sizing; women typically take one size down.

 
Shipping calculated at checkout.

You may also like

Product Details

One strap, zero lines — Y not?

The Y-back takes the thong one step further: a single elastic strap down the back, a sculpted pouch up front, and 100% cotton everywhere it touches. Barely there, completely comfortable — and nothing shows under anything.

Fabric
100% Cotton. Soft, breathable, and natural against the skin — the broken-in feel of a favorite tee, from the first wear.

Fit & Silhouette
Men's low-rise cotton Y-back thong — sits below the natural waist with a signature Y-back elastic strap and minimal coverage.

Contour Pouch
Sculpted 1-ply contour pouch with center-seam construction — light lift and natural shape, right where you want eyes to land.

Leg Openings
Clean elastic binding sits flat against the skin — no digging, nothing to adjust.

Waistband
1.5" exposed elastic waistband with the new signature C-IN2 logo in repeat.

Fit note
True to size. For a looser fit, go one size up.

Care
Machine wash.
Imported.

Core

C-IN2's foundation — every essential silhouette, cut in soft, breathable 100% cotton that feels better the longer you own it. The drawer you build once and reach for every day.

Dark Yarn is an independent retailer. C-IN2 New York is not affiliated with Dark Yarn or its philanthropy fund.

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