The SharperBlade fits 100% of all Weed Whackers on the market that have a removable trimmer head. The secret is in the SharperBlade’s “universal mounting system.” You just select one of the several “centering” washers that fit your equipment and place it in the center of SharperBlade’s mounting hole. Then, follow the easy, step-by-step, fully illustrated instructions. (The only models the SharperBlade will not install onto are two (2) electric brands – Black & Decker electric and Sears Craftsman electric, because the trimmer head cannot be removed. Toro electric trimmers require an adaptor – sold separately)