Hex Bit Wera 840/1 IMP DC 4 mm — alloy tool steel, impact-rated hex bit

Wera Hex Bit 840/1 IMP DC 4 mm is an impact-rated hex bit made from alloy tool steel, crafted to deliver dependable torque transfer and extended service life. The 4 mm hex profile is engineered to fit hex fasteners precisely, while the impact-rated construction allows use with impact drivers and power tools for demanding fastening tasks. The bit's geometry and material selection focus on wear resistance and reduced deformation under high loads.

Advantages

The bit's alloy tool steel composition and heat treatment provide a balance of hardness and toughness that reduces breakage and rounding of hex profiles. Impact-rated design absorbs shock loads from impact drivers, maintaining a secure fit during repetitive fastening. Compact length and standardized 1/4-inch drive compatibility ensure broad compatibility with bit holders and quick-change chucks. Surface treatment increases corrosion resistance and improves service life in workshop and jobsite environments.

Suitable for

• Driving and removing 4 mm hex screws with impact drivers and power tools
• Heavy-duty fastening in metalworking, construction, and mechanical assembly
• Professional repair and maintenance tasks requiring repeatable torque application
• DIY projects where durable, impact-rated bits are preferred

Key specifications

• Bit type: 4 mm hex (internal hexagon)
• Material: alloy tool steel with heat treatment for improved hardness and toughness
• Impact rating: designed for use with impact drivers and power tools
• Drive interface: standardized 1/4" hex drive compatible with common bit holders
• Length: compact design suitable for tight access (length varies by batch)
• Surface finish: corrosion-resistant treatment for enhanced durability

How to use

Insert the 1/4" drive end of the Wera 4 mm hex bit securely into a compatible bit holder, quick-change chuck, or impact driver. Align the hex profile with the fastener recess and apply steady, controlled pressure while engaging the tool. For impact drivers, start at low speed to seat the bit, then increase power as needed. Inspect the bit and fastener engagement periodically during extended use to avoid cam-out and to ensure consistent contact between bit and fastener.

Usage recommendations

Use the bit with tools rated for impact use and appropriate torque settings for the fastener material. Replace the bit if signs of rounding, chipping, or excessive wear appear. Store bits in a dry environment and use compatible bit holders to minimize lateral stress and prolong service life.