Wera 840/4 Z Hex Screwdriver Bit, 4 mm, 89 mm Length, 1/4" Hexagonal Shank

The Wera 840/4 Z Hex screwdriver bit is a professional-grade tool engineered for precision and durability in demanding fastening applications. With a 4 mm hexagonal tip and an extended 89 mm length, this bit provides excellent reach and access to recessed screws. It features the specialized Hex-Plus profile, which increases the contact surface area within the screw head, significantly reducing the risk of rounding out the screw and ensuring efficient torque transmission.

Advantages

The primary benefit of this bit is the Hex-Plus geometry, which prevents the common notching effect that often damages screw heads during high-torque operations. By distributing pressure more effectively, the bit protects the integrity of the fastener while allowing for higher force application. The tough, viscous material composition ensures the bit resists premature wear and breakage, providing a long service life even under heavy industrial use. Its standard 1/4 inch hexagonal shank makes it highly versatile, allowing for quick and secure attachment to a wide variety of power tools and manual bit holders.

Suitable for

• Assembly of mechanical components
• Industrial maintenance and repair tasks
• Furniture assembly requiring hex fasteners
• Automotive interior and engine bay work
• General construction and workshop fastening

When it may not be suitable

This bit is specifically designed for 4 mm hexagonal socket screws and will not fit other fastener types such as Torx, Phillips, or slotted screws. It is not intended for use with impact drivers that exceed the torque ratings of standard manual or power tool bit holders, as extreme impact forces may cause premature wear.

Key specifications

• Tip size: 4 mm Hex
• Length: 89 mm
• Shank: 1/4 inch hexagonal
• Profile: Hex-Plus
• Material: Tough, viscous steel
• Compatibility: Holders as per DIN ISO 1173-F 6.3

How to use

To use the Wera 840/4 Z bit, insert the 1/4 inch hexagonal shank into a compatible bit holder or power tool chuck until it clicks into place. Ensure the bit is fully seated in the screw head before applying torque. Maintain axial pressure to keep the bit engaged with the fastener, and operate the tool at a controlled speed to prevent cam-out or damage to the screw head.

What to consider before purchase

• Verify the size of your hex socket screws to ensure a 4 mm bit is required.
• Check the compatibility of your tool holder with 1/4 inch hexagonal shanks.
• Consider the depth of the screw access to ensure the 89 mm length is appropriate for your specific task.

Usage recommendations

For optimal performance and to extend the life of both the bit and the fasteners, always ensure the bit is clean and free of debris before use. Replace the bit if you notice signs of deformation or wear on the hexagonal edges.