UV321 13″ (330mm) Tri-Edge Tapered ARS Pole Saw & Hand Saw Replacement Blade. The use of a blade with a tapered profile and teeth that do not have conventional “set” achieves a very fast cutting blade because of it’s efficiencies in creating a narrow kerf where much less wood is removed with each cut. Tapered blades are much more flexible and should be used with finesse rather than with brute strength. Specifications: Manufacturer: ARS, Length: 13-inch, Teeth per inch: 6.35 Hardening: Impulse Mount: Dual Saw Blade Terms:Blade Profile: The two common blade profiles are “tapered” and “non tapered.” The tapered blade is thicker at the bottom where the teeth are and thinner at the top following edge. On a tapered blade the teeth do not have “set” (pushed left and right) therefore the blade following the teeth must be thinner to prevent drag in the saw kerf. A non-tapered blade has the same thickness from the top to the bottom. The teeth on a non-tapered blade have “set” to create a wider kerf at the teeth so the remaining blade can follow through the cut without drag. Typically a “non tapered” blade is more rigid than the tapered blade. Tooth Style: The three sided or tri-edge tooth has edges on both sides and across the top of the tooth. This style tooth cuts much faster then the conventional two sided tooth. The advantage of the conventional two sided tooth is it is easier to sharpen. Impulse hardening is the most common method for hardening saw teeth. The process involves using electrical impulses to create a very hard layer on the saw tooth edge. The advantage of impulse hardening is a much longer tooth life. The disadvantage of an impulse hardened tooth is it cannot be sharpened. Mount: Many saw blades are punched with two different mounts (hole patterns) to allow one blade to serve as a pole saw blade and at the same time a replacement blade for its respective hand saw. This “Dual” mount allows tree service professional to order just one blade for both uses.