Liquid Force Melody Comp 2017 Flex-Span Neoprene Fits like a second skin. 38-panel Flex-Architecture design. PVX is Liquid Force's best lightweight, soft, stretchable, and flexible high-impact flotation foam. Minimal taper and maximum stretch so the Flex can zip up tight without restrictions. Reversible - If the mood strikes you, flip out this vest for a new look.