Fits: 135 – 175 HP Optimax/Optimax ProXS and the 150 – 200 HP EFI. Fits: Mercury Engines. Locks the outboard motor in the forward position while trailering, greatly reducing the damaging effects of road shock. Does not “tie” engine’s lower-unit to trailer, eliminating excessive pressure on hydraulic seals and scuff marks. Small compact mount can be easily stored in just about any boat compartment. Constructed of black powder-coated steel with stainless steel pins.