Durable High Quality Completely Weatherproof Long Lasting Universal Clamp-on Mount Cup Holders. Universal clamping system, mounts on 1 1/2 to 2" OD size range of round & square boat pipework. Once installed, it will rotate 360 when pushed around pipe but will not migrate down, unless forced. Smart Cup - Fits, 20 & 30 oz, larger Tumbler Cooler Cups & a can with or without foam insulator. Stabilized to resist saltwater, UV damage, harsh outdoor elements & abuse, comes w/slot for pliers.