This Bumper is molded from a stiffer formulation to handle larger watercraft. The bumper is the same as the #45 with the addition of a .75" Lip. There are three recessed molded in mounting holes for easy installation. The bumpers are rotationally molded for long lasting quality. Three recessed mounting holes are molded into the bumper. Use up to a quarter inch lag bolt with a nut and washers for easy installation on to any wood or metal dock or pier. Made in America