4 Pack, Heat Hardened (longer life) Edger Blades Replace Ryobi 613223, Echo 720-237-001, Stihl 4133-713-4101, Maruyama 216062. Green Machine 237001 Set of 4 blades Heat Hardened for longer life, finished, unsharpened. 7.87" Long, 1.97" Wide, .12" Thick, 1" Center Hole