The grass gator 4690 extra heavy duty replacement blades, part number: 4690 are designed for the grass gator extra heavy duty trimmer head, part no: 4680, and the older 4650. Do not use these blades on any replacement head other than the grass gator 4680 and 4650. This replacement pack contains 3 tough solid steel blades. The grass gator blades are easy to install, and directions for installing the new blades are included on the package.