The Klein Tools Bi-Metal Hole Saw, 2-1/4-Inch (31021) cuts precise 2-1/4" (5.7 cm) holes in stainless steel, mild steel, drywall, ceiling tile, laminates, wood and plastic. This is a bi-metal hole saw designed for electrical, mechanical and general construction work where one cutter has to handle metal and softer materials alike.

At 2-1/4" (5.7 cm) and 5.4 oz (153 g), this cup has a long cutting edge in contact with the work. Bi-metal construction and the variable tooth pattern are what keep a cut that size from turning into a chatter fest in steel.

On the 2-1/4" (31021), bi-metal construction is optimized for cutting steel, and Klein designs it for the fastest, most consistent and longest-lasting performance. The VARI-RAKER ET tooth pattern runs a variable 4/6 teeth per inch.

Getting the plug out is half the job with any hole saw, and a 2-1/4" plug is no exception. Klein uses a unique pattern of access slots in the cup wall that provide clearance and leverage, so you can push or pry the waste plug free with a screwdriver instead of beating on the saw.

Klein builds the 31021 with a thicker, heavy-duty back plate designed to withstand jobsite abuse. It mounts on the Klein Tools quick-release arbor or on traditional threaded arbors, so it fits into whatever setup you already run. The arbor is a separate purchase.

Nearby Klein bi-metal hole saw sizes include the 2-1/8" (31020) and 2-1/2" (31022), if your layout calls for a different diameter.

Who should buy it: electricians, HVAC and plumbing techs, and remodelers who need 2-1/4" holes in steel enclosures and panels as well as wood and drywall, and want one bi-metal saw that handles all of it.

A Bigger Bite in Steel

The Klein Tools Bi-Metal Hole Saw, 2-1/4-Inch (31021) cuts clean 2-1/4" holes in steel and everything softer, and lets go of the plug easily.

• Who it's for: Trades who cut through steel boxes, panels and enclosures as often as wood and drywall.
• Why it stands out: Bi-metal teeth tuned for steel, a plug-friendly slot pattern and a thicker back plate.
• Worth knowing: Arbor sold separately. Choose the Klein quick-release arbor if you change sizes often.

• What materials can the Klein 31021 cut? Klein rates it for stainless steel, mild steel, drywall, ceiling tile, laminates, wood and plastic.
• Does it come with an arbor? No. It needs a hole saw arbor, sold separately. It fits the Klein Tools quick-release arbor and traditional threaded arbors.
• How deep does it cut? Klein lists a 2" (5.1 cm) drilling depth.