Star Knobs are handy, attractive, quick-tightening knobs for mounting brackets, leeboards, kick-up rudders, and so on. We use these in the Eastport Nesting Pram and the Take-Apart Passagemaker Dinghy. Even cold fingers can spin these on and off. These measure 3" in diameter, 3" deep, and have 5/16" x 18 threads. Marine grade so they won't corrode.