Hex Key (Allen Key) Wera 4.0 mm short with ball end, model 950 PKS

The Wera 4.0 mm short hex key (model 950 PKS) is a compact, precision tool engineered for driving hex (Allen) fasteners in confined or partially obstructed spaces. Featuring a short shaft for strong, controlled torque and a ball end that permits engagement at slight angles, this hex key is intended for professional technicians and DIY users who require reliable access and repeatable performance during assembly, maintenance, and repair tasks.

Advantages

The short shaft gives improved leverage and tactile control compared with longer keys in tight work areas, while the ball end allows insertion at angles up to approximately 25–30° for easier engagement of fasteners that are not perfectly aligned. Manufactured with hardened steel and a precision-machined hex profile, the tool provides secure fitment in fastener sockets to reduce rounding and slipping. Its compact size makes it convenient to carry in a toolbox or pocket and suitable for frequent use in workshops and on-site service calls.

Suitable for

• Driving and removing hex (Allen) screws and bolts in tight or recessed locations
• Assembly and disassembly of furniture, machinery, and electronic enclosures
• Maintenance and repair work where angled access is required
• Professional workshops, service technicians, and home DIY projects

When it may not be suitable

This short 4.0 mm hex key is not intended for tasks that require very high torque; for heavy-duty loosening of seized or high-torque fasteners a longer lever or a dedicated torque tool is preferable. Also, when perfectly straight engagement is required in deep sockets, a longer straight hex key may provide better reach and control.

Key specifications

• Hex size: 4.0 mm
• Type: short shaft hex key with ball end
• Ball end: enables angled engagement
• Material: hardened tool steel (precision-machined hex profile)
• Use: manual hand tool for driving hex fasteners

How to use

Select the 4.0 mm hex key and align the hex profile with the fastener head. For direct engagement insert the short shaft fully into the fastener socket to achieve maximum contact. When access is obstructed or the fastener is at an angle, use the ball end to engage the fastener at a slight angle and apply steady torque. Avoid excessive force beyond the intended manual torque to prevent fastener rounding or tool damage. After use, store the hex key in a holder or toolbox to protect the precision tip.

What to consider before purchase

• Confirm that the fastener head uses a 4.0 mm hex profile
• Assess whether the short shaft length and ball end are suitable for the working space and access angles
• For high-torque or deeply recessed fasteners, consider a longer key or a different tool

Usage recommendations

Use this 4.0 mm short Wera hex key for routine assembly and maintenance where space is limited; engage with the straight shaft when possible for maximum torque and switch to the ball end only when angled access is necessary to maintain control and protect fastener heads.