These solid blocks with No-Skid bottoms provide easy, safe, and convenient kayak transport system for vehicles without a rack. If you"re certain you will not be using blocks in conjunction with factory or after-market rack bars, our solid No-Skid blocks and kit offer a longer life and higher elevation over blocks with pre-cut rack bar slots. Includes four blocks, two 18" V-style bow/stern straps, two 13" Over-the-Hull straps, and a mesh storage bag.