(1)---UNIVERSAL FIT -- each of our blades will fit either 25.4mm Arbor (same as 1”) or a 20mm Arbor with included “reducer washer” with YOUR "Blade Hardware". (2)--- IMPORTANT |BLADE HARDWARE: A Blade will {not} fit onto the Trimmer Axle Shaft by itself like the String Line Dispenser Spool will, so you must acquire "Blade Hardware" (mounting adapter kit or parts) that consists typically of two small discs; one has a raised circle on it that the blade hole (arbor) fits onto, the 2nd small disc is the cap disc, then screw on the Nut and apply a Cotter Pin. Sorry, we DO NOT supply blade hardware. (3)--- CARBIDE MIX in our teeth is proprietary and 2nd to none. Just Tungsten is not enough; additives like: Hafnium, Tantalum, Titanium, Molybdenum, Silicone, Zirconium, Boron, Niobium, Chromium, & Vanadium, make for a better Carbide Mix for longer lasting teeth. (4)--- ULTRA HIGH RPM: Our blade is built for any RPM even super high RPM Trimmers (10,000+ rpm). Manufactured with a more flexible steel as compared to the much more brittle steel found with table saw blades (table saw blades can shatter if they hit an obstacle, plus they are only built for approx. 3,450 rpm so they should never be used with gasoline powered Garden Trimmers. (5)--- RENEGADE BLADE is the ONLY Carbide Brush Blade BRAND on AMAZON that has a {REPORT} from the foremost Testing Laboratory: UL, LLC. (6)--- CHOOSING THE CORRECT BLADE: Blades line up on a polarity scale with maximum TEETH on one end [for CUT] all the way to maximum CAVITIES [for GRAB] on the other end. EXAMPLE: Wood tree limbs require more teeth and no cavities, and wispy flexible brush or grass requires maximum grab as teeth alone just pushes grass over without cutting. THEREFORE: You must pick a {Teeth & Cavity Pattern} that best suits your material being cut. We offer blades to handle any: Wood, Bushes, Brambles, Hedging, Brush & Grass.