As more contractors add impact drivers to their toolboxes, manufacturers have responded by offering ever- expanding lines of bits and accessories that are rated for higher-torque duties.

Milwaukee Electric Tool Corp. builds on its existing collection of Shockwave impact bits with the addition of thin-walled hole saws, introduced this year. The company recently sent ENR a set to try out with an 18-volt impact driver.

The thin-walled hole saws range in diameter from ¾ in. to 1½ in. and are fitted with ¼-in. quick-change hex shanks. Like other impact saws, Milwaukee's use a raised shoulder to keep the driver from breaking through the work area. Each of the hole saws includes an ejector spring that forces waste material out of the saw cavity.

Milwaukee claims the impact saws drill through metal 40% faster than standard bi-metal hole saws. We took Milwaukee's 11/8-in. saw for a spin and compared it to a DeWalt impact-ready saw of the same size. The saws drilled through light metal with roughly the same speed, and they had no problem ejecting metal cores. However, both struggled with heavier-gauge metal, and, in one instance, a plug jammed in the Milwaukee bit.

Priced similar to the competition, the Milwaukee hole saws retail for about $12 to $15 apiece and come in larger kits, too. Also now available in the Shockwave line are 6-in. and 12-in.-long magnetic bit holders, useful for hard-to-reach places. The company also has introduced a set of impact-rated nut drivers with handy color-coded size indicators and a 30° knuckle adaptor for offset driving.