FLEXIKOLD OFFERS FEATURES NOT FOUND IN OTHER COLD GEL PACKS Durability: Nylon cover is much more durable than vinyl. Will not dry out or crack like vinyl or polyurethane. covers. Flexibility Duration of Cold Quality of Cover: Constructed of extra-thick flexible nylon material. Double sealed to prevent leaking. Finished edges prevents seams from separating. Smooth high quality feel. Quality of Gel: Gel pack has ability to maintain complete contact with the treated area. Can completely wrap around a 360├╕ area.