The Ko-ken 3/8″ Drive 6 Piece Wobble-Fix Extension Set (KOPK3763/6) is a professional-grade socket extension system designed to provide both rigid and controlled angular access in tight or obstructed fastening areas.

Manufactured in Japan, this set combines Ko-ken’s unique Wobble-Fix dual-function design, allowing each extension to be used as either:

• a straight extension for full torque transfer
• or a controlled wobble extension for up to ~15° offset access

This makes it one of the most versatile extension systems for automotive and industrial trade work.

What “Wobble-Fix” Means

Ko-ken’s Wobble-Fix design gives you two working modes in one extension:

• Fix mode: locks the socket in place for maximum stability and torque
• Wobble mode: allows controlled angular movement (approx. 15°) for access in tight spaces

 This eliminates the need to carry separate wobble and straight extension sets.

Key Features

• 6-piece 3/8″ drive extension set
• Dual-function Wobble-Fix design (fixed or flexible use)
• Length range: 32mm to 250mm
• Precision-machined Ko-ken Japanese engineering
• Tight tolerance fit reduces socket slop and wobble loss
• Suitable for both light and heavy workshop use
• Supplied in organised set for quick size selection

Included Sizes

This set includes:

• 32mm extension
• 50mm extension
• 75mm extension
• 125mm extension
• 150mm extension
• 250mm extension

 Covers everything from tight engine bay access to deep recessed fasteners.

When to Use Wobble vs Fixed Mode

Use FIX mode when:

• high torque is required
• breaking loose tight fasteners
• precision control is needed

Use WOBBLE mode when:

• fasteners are slightly offset or obstructed
• space is restricted in engine bays or machinery
• you need angled socket access without a universal joint

Applications

This extension set is widely used in:

• automotive repair and servicing
• diesel and heavy vehicle maintenance
• industrial shutdown and plant work
• mining and field service environments
• mechanical and fitting workshops
• construction equipment repair

Why Professionals Choose Ko-ken Extensions

Compared to generic wobble extension sets, Ko-ken delivers:

• significantly tighter socket fitment
• reduced flex under load
• smoother torque transfer
• longer service life under trade conditions
• better control in both fixed and angled modes

This is why Ko-ken extensions are commonly used in professional workshop toolkits.

Straight vs Wobble Extensions (Important Context)

Unlike standard wobble-only extensions, Wobble-Fix gives you:

• the strength of a straight extension when needed
• the flexibility of a wobble extension when required
• fewer tools needed in your kit

 One system replaces two separate extension types.

Product Specifications

• Product code: KOPK3763/6
• Drive size: 3/8″ square drive
• Pieces: 6
• Lengths: 32mm, 50mm, 75mm, 125mm, 150mm, 250mm
• Type: Wobble-Fix / dual-function extension set
• Material: High-strength alloy steel
• Finish: Chrome plated
• Origin: Japan

Who This Set Is For

Ideal for:

• professional mechanics
• diesel and heavy vehicle technicians
• industrial maintenance fitters
• workshop tool kits requiring flexibility
• trades working in confined mechanical spaces