Davis Happy Troller Folding Trolling Plate Small Troller fits outboard motors from 20 to 50hp. Large Troller fits outboards over 50hp.A significant invention in the sport of troll fishing, Happy Troller mounts on the anti-cavitation plate to allow fine control of trolling speed. At cruising speed, your boat's stability is enhanced. Happy Troller is the answer to correct trolling speed. Use it year-round in all boating activities; salt and fresh water. Key Features: Maintains stability in bow-light boats Smooths out ride in rough water Reduces porpoising and cavitation Made of only highest quality stainless steel and marine aluminum; clear anodized aluminum finish Installs in 15 minutes Stainless steel mounting hardware and installation & operating instructions provided with each unitThe Davis Happy Troller Folding Trolling Plate has three positions. Reduces troll speed in "down" position Acts as a stabilizer in "up" position Middle position for added flexibility Click to Download Happy Troller Installation Instructions.