Fangrui Product Details A Must Have For Boat Trailers: Trailer Bunk Slides Pads Definitely Launching And Loading Boat On And Off Trailer Quickly With Minimal Effort.makes Loading And Unloading On/off The Ramp Much Easier! Fit For Almost Any Bunk Trailer,includes 2inch, 4inch 6inch Boat Trailer Bunk Slides.boat Weight Limitation: 1,500 Lbs For Fiberglass Boats, 4,000 Lbs For Metal Boats. Works On Bunk Trailers For Unpainted Bottom Boat Pontoon Boat/jon Boats/jet Ski//waverunner/fishing Boats. Its Not Recommened For Painted Bottom Boat,because May Scratch The Bottom Paint. Our Boat Trailer Slides For Bunk Are With Recessed Screw Holes For A Firm Mount. Just Be Make Sure The Screws Drop Into Countersink Area To Prevent Scratching Hull. Dont Release From The Trailer Hookup Until Backed Into The Water.just Remember Unhook Boat Before Taking Boat Out Of Water.because Trailer Slides For Bunks Are Very Slick And Your Boat Slide Off On A Steep Boat Launch. More Warm Tips Pls See Below Information And Instruction. Note: Installation Gui