Greenlee GSB12 Kwik Stepper® #12 Step Bit – 1-3/8" Max Diameter

Industry Standard for 1" Conduit. Steam Oxide Heat Shield. Fast, Bur-Free Knockouts.

The Greenlee GSB12 is the professional’s choice for large-diameter drilling in electrical panels, junction boxes, and metal studs. Engineered specifically for the trades, this #12 Kwik Stepper® is designed to provide the perfect 1-3/8" hole required for standard 1-inch conduit fittings. While standard bits struggle and overheat at this size, the GSB12 features a premium Steam Oxide finish that significantly reduces friction and heat, extending the life of your cutting edge even in high-torque applications.

Equipped with a non-walk split-point tip, the GSB12 bites into the metal immediately—even on curved surfaces—eliminating the need for a center punch. Its dual-fluted design ensures efficient chip removal and a cooler operation, resulting in clean, symmetrical holes that are ready for fittings with minimal deburring.

Key Features & Professional Benefits:

• The 1" Conduit Standard: Perfectly sized at 1-3/8" to create the exact knockout required for 1-inch electrical conduit and connectors.
• Steam Oxide Performance Finish: Specialized coating prevents "welding" of metal to the bit and dissipates heat, ensuring a longer tool life in heavy-gauge steel.
• No-Walk Split-Point Tip: Self-centering tip starts on contact, preventing the bit from wandering across expensive panels or finished surfaces.
• 10 Precision Hole Sizes: A single tool that allows you to drill in increments from 7/8" up to 1-3/8", replacing a dozen traditional drill bits.
• Rapid Chip Removal: The dual-flute geometry clears debris faster, keeping the bit cool and preventing the clogging that leads to bit failure.
• Laser-Etched Size Guide: Permanent, easy-to-read markings are etched inside the flute so they won't wear off under heavy industrial use.
• Anti-Slip 3/8" Shank: Features flat-milled sides to ensure a rock-solid grip in your drill chuck, allowing for maximum torque transfer without slipping.

Product Specifications:

Efficiency for the Industrial Electrician

The Greenlee GSB12 is more than a drill bit; it is a specialized knockout tool. By combining Greenlee’s legendary durability with a dual-fluted cutting system, this bit allows you to move through high-volume panel work with speed and accuracy. For the professional at The Fastener Group who demands a tool as tough as the jobsite, the GSB12 is the definitive choice for large-scale electrical installations.

Stop struggling with undersized bits or hole saws. Upgrade to the Greenlee GSB12 and get the 1-3/8" precision your conduit runs require.

Build Your Professional Knockout Kit 

Pair your GSB12 with these trade-essential tools to ensure your large-diameter drilling is clean, professional, and protected.

• [Cold Galvanize Spray] – The professional standard for treating new knockouts; prevents rust and corrosion on raw steel edges instantly.
• [Unilite SLR-1750 Rechargeable Site Light] – A heavy-duty 1750 lumen work light with a 180° folding stand and powerful magnets. Features an integrated USB power bank to keep your devices charged on the jobsite.
• [Stabila 11901 Pocket Level PRO Magnetic] – Ensure every junction box and conduit run is perfectly plumb and level.
• [Watson 2757 Fabulous Fabricator Gloves] – Heavy-duty goatskin protection to keep your hands safe from the hot, sharp metal curls generated by large step bits.