Listings commonly show all-around or fully elastic construction—elastic on all four sides—to create a snug, secure fit on the mattress.
Some microfiber sets list a 200 thread count and describe the fabric as lightweight, while some jersey/cradle sheets mark thread count as not applicable.
Descriptions list jersey knit (noted as ultra-soft and breathable for some items), brushed microfiber, and polyester backing on some sets.