Sei Fitted Sheet

The Sei Fitted Sheet is 100% cotton, woven in a sateen weave at 600 thread count — the highest thread count in the MATTEO collection. Thread count measures the density of the weave, but it works alongside yarn quality and weave balance to determine how a fabric actually feels. Sei uses a 120/2 Ne yarn in both warp and weft, which produces a face that is silky and smooth without the stiffness that typically comes with higher counts. MATTEO has not gone above 600 TC precisely because denser weaves tend to trap heat and resist movement.

The Sei Fitted Sheet has a full-perimeter elastic band encased in the bottom seam with a high-density stitch, so the elastic holds its shape through repeated washing. The 16-inch pockets are finished with a flat felled seam tacked down at the top corner, reinforcing the corners that take the most wear. The sheet fits mattresses up to 20 inches deep comfortably.

The Sei Fitted Sheet is available in Twin (39 x 75 x 16 inches), Twin XL (available), Full (54 x 75 x 16 inches), Queen (60 x 80 x 16 inches), King (78 x 80 x 16 inches), and California King (72 x 84 x 16 inches). All sizes share the 16-inch pocket depth and full-perimeter elastic construction. If you are unsure which size fits your mattress, match the fitted sheet dimensions to your mattress width, length, and depth before ordering.

Yes, the Sei Fitted Sheet is garment-washed after dyeing, which gives it a softer, more lived-in feel from the first use. Garment-dyeing is an artisanal process, and MATTEO allows for a shade variation of plus or minus 10% from dye lot to dye lot. If you are ordering multiple pieces to match, purchasing them together from the same dye lot is the most reliable way to get consistent color. You can learn more about MATTEO's garment-dyeing process here.

Wash light and dark colors separately in a lukewarm cycle with a gentle detergent and a cool rinse. Do not overload the machine, as this can damage the long cotton fibers. Tumble dry on low heat and remove promptly to reduce wrinkling; line drying gives the best result. If you prefer a crisp look, press the sheet while slightly damp on the Lightweight Cotton or Medium iron setting. Avoid bleach and whitening agents on garment-dyed colors; bleach is safe on white cotton only.

Sateen and percale are both 100% cotton weaves, but they feel quite different. Sateen, like Sei, has a smooth, silky face created by a float-heavy weave structure, while percale is a one-over-one weave that produces a crisper, matte finish. Linen, by contrast, is derived from the flax plant and has a textured hand that softens over time and breathes well in warm climates. Sei at 600 thread count is the right choice when you want a cool, smooth surface with a subtle sheen; for a crisper feel, MATTEO's Tru Fitted Sheet in percale is worth considering, and the Vintage Linen Fitted Sheet suits hot sleepers who want natural breathability.

The Sei Fitted Sheet is made from 100% cotton with non-toxic dyes, so it does not contain synthetic fibers or harsh chemical finishes. The garment-washing process removes surface sizing and pre-shrinks the fabric, which means the sheet arrives already broken in rather than stiff. Cotton at this weave density is gentle against skin and less likely to pill or abrade than lower-quality weaves. For those with very reactive skin who also need maximum breathability, MATTEO's Vintage Linen Fitted Sheet is an alternative worth comparing.

Hotel linens at the upper end typically use long-staple cotton in a sateen or percale weave at 300 to 600 thread count, prioritizing durability and a consistent smooth hand over decorative finishes. The Sei Fitted Sheet meets that standard: 100% cotton, 600 thread count sateen, with a reinforced flat felled seam at the corners and a full-perimeter elastic band built to hold through repeated industrial-grade washing. The garment-washing finish gives Sei a softness that most hotel sheets reach only after years of laundering. Designed and manufactured by MATTEO in Los Angeles, it is made to last well beyond a single season.