Product Code & Back Cuts

iSwim Product Code & Back Cuts System

Introduction

Every iSwim thong, brief, or swimwear comes with a unique product code — and it’s more than just an order reference. Our codes tell a story: when it was designed, what type of cut it features, and even which version of the back cut it includes. If you've ever wondered, “What does u3020 or s3011 actually mean?”, this guide is for you.

Product Code System

iSwim’s underwear and swimwear codes reflect the design type and year of release.
From 2009 to 2016, product codes consist of 6 characters. The first two digits indicate the year, and the third character shows the category: 'u' for underwear, 's' for swimwear.
For example, 13u527 means it’s an underwear design from 2013, the 527th style since 2009.
From 2017 onwards, codes are 7 characters long. The 4th character represents a subcategory:
1 — 15mm waistband; 3 — 8mm strap; 5 — bikini-type 8mm strap; 7 — 15mm inset-style.
Even numbers (2, 4, 6, 8) indicate unique or experimental designs.
An additional suffix indicates the back cut, such as -H1.
For example: 21u3009-H1 means it’s an underwear style (u3009) launched in 2021 with a H1 (super-low rise, half-back) back.

Back Cut Code System

💡 Since 2017, styles with a 4th code digit of 1, 3, 5, or 7 often allow back piece customization (some options may require an additional fee).
New designs (from 2017) are not compatible with old designs (2009–2016), so back cuts like B1, H1, or Y1 cannot be applied to earlier versions.
We offer a variety of back styles, ranging from sexy to playful. Each back type is available in four waist heights (Take Y-thong as an example) :
Y0 — low rise; 　Y1 — ultra-low rise;
Y2 — extreme-low rise; 　Y3 — extreme rise (minimal).
Y1 is the default height for most of our Y-style thongs.

Bonus Chapter

Ultrarotic Codename：U•L•T•A•R

Beyond patterns and sizing logic lies something cosmic.

At the edge of Y3, fabric begins to defy physics, giving birth to a frequency only detected by sensual lifeforms across the galaxy.
They call it: Ultar Sexy™.

⚡ Ultar Sexy™ — Interstellar Low-Rise System

Y0 — low rise (Earth standard)
Y1 — super-low rise (reduced gravity)
Y2 — ultra-low rise (cheekwave resonance)
Y3 — extreme-low rise (boundary collapse)
U∞ — Ultar sexy (zero fabric, pure signal)
“What you call fabric, they consider ceremonial.”
“Sexy isn’t a cut — it’s a culture.”