Shop for OP-TEK® (EVA) sheets. OP-TEK® is a soft, flexible EVA copolymer that provides outstanding patient comfort when used as a liner for rigid socket frames. OP-TEK® Flex is specially formulated to maintain more consistent walls during forming compared with other flexible plastics. OP-TEK® flexibles come in semi-transparent white, black, and in black/white (bi-laminated). Custom cuts available. Stocked materials typically ship in 2-5 business days. Can’t find what you need? Get a quote.