Renegade Blade 4pk-10-40t - Brush & Brambles Specialty Carbide Brush Cutter weed eater Blades, 254mm diameter Pack of {4} -- 10"-40 teeth -- Brush & Brambles Specialty -- Carbide Tipped Trimmer Brush cutter Blades, by RENEGADE BLADE BLADE ATTACHMENT PARTS: Our blades are "Universal Fit" provided you FIRST acquire "Blade Kit" parts for your Trimmer model, (we don't sell these parts). IMPORTANT&gt;&gt; A blade does {NOT} fit directly on the tiny 5/16" axle that the "String Spool" screws onto, ALL string trimmers require some type of blade mounting parts (normally 2 small discs, nut, and cotter pin) to run a blade (YouTube can show this). We offer TWO arbor sizes: 25.4mm (same as 1") & also 20.0mm with reducer washer. CARBIDE -- is estimated to last 10x longer than plain steel but does not cost 10x more creating incredible value. The CARBIDE MIX in our teeth is proprietary and 2nd to none. FIVE BLADE TYPES -- All 5 specialty types of blades we offer are as follows: (1) RSB. multi-use: 8-80t, 9-100t, 10-120t... (2) RSB. brush & brambles: 8-32t, 9-36t, 10-40t... (3) Red RAZOR Hybrid combination blade: 8-56t, 9-68t, 10-80t... (4) Green VIPER Hybrid brush & brambles: 8-44t, 9-48t, 10-52t... (5) Blue HAWK Hybrid brush only: 8-20t, 9-20t,10-20t RENEGADE BLADE is the ONLY Carbide Brush Blade BRAND on Amazon that has a {REPORT} from the foremost Testing Laboratory: UL, LLC.