Smooth-skin 1.5 mm neoprene is water- and abrasion-resistant for long-lasting durability and protection. Shock cord band adjusts to snugly fit your kayaks cockpit combing, just tie a simple knot to secure it in place. Large size fits cockpits 40-57 inches in length. Note: When placing cover on cockpits at the upper end of the size range, it can be a tight fit. Leaving the cover on the boat for at least 24 hours will stretch it a bit and should make it easier to put it on next time.. . Keep your kayak's cockpit dry, clean, and critter-free with the NRS Super Stretch Neoprene Cockpit Cover..