3/8" Hex Hole Saw Arbor Shank with 3-Flat Shank Milwaukee hole saw arbors are made from hardened carbon steel and alloy steel for greater durability. The 49-56-7010 features a hex shank which can be used with any 3/8" Extension. Features: 3/8" Shank 3-Flat Shank Up to 1-1/4" Since its founding in 1924, Milwaukee has focused on a single vision: To produce the best heavy-duty electric power tools and accessories available to the professional user. Today, the Milwaukee name stands for the highest quality, durable and reliable professional tools money can buy.