Most sets specify deep pockets that fit mattresses up to 16" deep. Fitted sheets in the listings are generally described as fitting mattresses up to 16" in depth.
A standard 5-piece split-king set typically includes one king flat sheet, two Twin XL fitted sheets, and two pillowcases.
Listings commonly describe 16" deep pockets and full-perimeter (all-around) elastic. Some sets also mention gripper elastic and top/bottom tags to make bed-making easier.
Descriptions highlight silky bamboo viscose with a twill weave for a cool, soft feel; double-brushed microfiber for an ultra-soft, wrinkle-resistant finish; and cotton sateen for a smooth, slightly luminous sheen.
Pillowcase sizes reported in the listings include roughly 20" x 40" (typical king) and about 21" x 40" in some sets, so dimensions vary slightly by set.