Ryobi ACFHRL2 Polycarbonate Bladed Trimmer Head Compatible with Ryobi 18-Volt, 24-Volt, and 40-Volt Strimmers (2 Pack) FIXED DUAL BLADES mean that you do not have to struggle with your trimmer line as it gets stuck SERRATED EDGES are ideal for thicker grasses that your strings may not be able to handle EASY INSTALLATION: simply push this trimmer head into the stringer socket and it automatically locks in place with assistance from the side push buttons FITS RYOBI STRING TRIMMERS: 18-Volt, Hybrid, 24-Volt, 40-Volt, RY40210, RY40210A FOR BEST USE: avoid using this accessory for edging, working alongside brick, chain, or wooden fencing