Bob's Machine Prop Nuts require no tools when removing your trolling motor propeller, making it easier to clean fishing line and weeds, or change propellers on the water! They feature over 25% more mass than most other units, creating a quieter troll. Each nut is machined for maximum precision and balancing with no engraved markings on the side to throw off it's perfect balance. The Matte Black ceramic coating is specially designed for use in salt water. It will not fade and provides superior corrosion resistance.