Hex Bit Wera 840/4 IMP 4 mm diamond coated alloy tool steel

Wera Hex Bit 840/4 IMP 4 mm diamond coated alloy tool steel is a hexagonal screwdriver bit engineered for use with impact drivers and bit holders. Machined from alloy tool steel and finished with a diamond coating, this 4 mm hex bit is intended to improve contact with screw heads and reduce cam-out during high-torque fastening operations. The bit’s construction balances hardness and toughness for repeated assembly, maintenance, and repair tasks in workshop and field environments.

Advantages

The diamond coating increases surface friction between the bit and fastener, improving slip resistance and reducing the likelihood of rounding screw heads. Alloy tool steel provides enhanced wear resistance and impact strength compared with standard tool steels, extending service life under frequent use. The bit is sized precisely to fit 4 mm hex sockets, ensuring a secure fit in compatible fasteners and minimizing wobble during operation. Designed for impact applications, the geometry and material combination deliver consistent performance when used with impact drivers and compatible bit holders.

Подходит для

• Монтажные и разборочные работы с 4 мм шестигранными крепежными элементами
• Техническое обслуживание и ремонт в мастерских и на выездных объектах
• Использование с ударными шуруповёртами и держателями бит
• Профессиональные и любительские проекты, требующие повышенной стойкости к срыву

Key specifications

• Bit type: 4 mm hex (internal hexagon)
• Material: alloy tool steel
• Surface finish: diamond coating for improved grip
• Intended use: impact driver compatible
• Application area: assembly, maintenance, repair
• Design: precision-machined tip for secure fastener engagement

How to use

Insert the 4 mm hex bit into a compatible bit holder or directly into the chuck/drive of an impact driver. Ensure the bit seats fully and locks in the holder to avoid axial play. Select an appropriate torque and speed setting on the impact driver suited to the fastener and material to prevent over-torquing. Apply steady pressure aligned with the fastener axis while driving or loosening screws. After use, wipe the bit clean of debris and store it in a dry, secure place to protect the diamond coating and maintain fit accuracy.

Usage recommendations

Use the bit with impact-rated holders and tools to match its design. Avoid using damaged or heavily worn bits on high-value fasteners to prevent damage to screw heads. Periodically inspect the diamond coating and tip geometry; replace the bit if excessive wear or deformation is observed to preserve fastening quality.