Convert your Gas or Electric String Trimmer into a string less trimmer! With its patented self-sharpening system , you"ll get 216 feet of nylon string in every blade. Safe to use on brick, concrete, and stone. This OEM blade fits the Sun Joe Sharperblade model SB601E however it also adapts to most gas and electric trimmers with a threaded shaft. Does not fit on Pop-head models such as Toro Electric, Black and Decker Electric, and Craftsman Electric. Blade must not exceed 10,000 rpm.