Screwdriver bit Wera 840/1 Z — Hex 3 mm, 25 mm length, 1/4" (25.4/4 mm) hexagonal shank

Wera 840/1 Z is a single screwdriver bit with a metric 3 mm hex tip and a total length of 25 mm. The bit has a 1/4" (25.4/4 mm) hexagonal shank designed to fit standard bit holders and quick-change chucks. Manufactured with a tough, viscous material and Hex-Plus geometry, this bit reduces the notching effect on hex socket screws and provides a more secure contact between tool and fastener. It is intended for tasks that require a short, robust bit for assembly, maintenance and repair work on equipment and machinery using metric hexagon socket fasteners.

Advantages

The Hex-Plus geometry increases the contact surface inside the screw head, minimising damage and extending screw life compared with conventional hex bits. The material and heat treatment deliver ductility and toughness required for use with hard materials, reducing breakage and wear. The 1/4" hexagonal shank ensures a secure fit in compatible bit holders, enabling efficient power transfer and reliable engagement in quick-change systems.

Suitable for

• Assembly and disassembly of machines and devices with metric hex socket screws
• Maintenance and repair tasks in workshops and service environments
• Use with bit holders, quick-change chucks and screwdrivers accepting 1/4" hex shanks

Key specifications

• Tip type: metric hexagon (3 mm)
• Overall length: 25 mm
• Shank: 1/4" (hexagonal) compatible with DIN ISO 1173-D 6.3 holders
• Geometry: Hex-Plus for increased contact surface and reduced notching
• Material properties: tough, ductile bit material designed for wear resistance
• Intended use: single bit for short-reach fastening tasks

How to use

Insert the 1/4" hexagonal shank into a compatible bit holder, quick-change chuck or screwdriver. Ensure the bit is fully seated and locked before applying torque. Use the bit for tightening or loosening metric 3 mm hex socket screws; apply steady, controlled force to avoid excessive side load. For powered drivers, select appropriate speed and torque settings to match screw type and material. After use, inspect the tip for wear or damage and replace the bit when contact profile is visibly degraded.

Usage recommendations

Choose matching holder systems that comply with DIN ISO 1173-D 6.3 to ensure secure engagement. For high-torque or repetitive industrial applications, monitor bit condition and replace regularly to maintain screw head integrity. Keep the bit clean from debris and lubricants to preserve the Hex-Plus contact geometry.