These high-speed variable pitch bi-metal hole saws are ideal for cutting perfectly round and accurate holes in metals, plastics and wood up to a depth of 35mm (1.3/8). They offer a hardened M3 steel cutting edge that is welded to a tough alloy steel body, making them very durable and hardwearing. The construction reduces the risk of shattering. The holesaws have four side slots for removal of slug, as well as a female threaded spindle for fixing to a 9.5mm arbor. It can be easily attached to power drills for a fast, clean, heavy-duty cutting action in stubborn materials. When metal cutting it is advisable to use a lubricant to prolong the service life of the hole saw, such as Stock No. 76109 – Metal Cutting Lubricant, 400ml.