Heavy Duty Gas Strut 300mm 400N Pair – M6 Threaded Ball Joint – With 4x L Brackets
✓ IN STOCK – FAST UK DISPATCH
Designed for external and load-bearing lid applications, this 300mm 400N heavy-duty gas strut pair provides stable lift support for medium-weight lids that need controlled movement and dependable hold-open performance. It is a practical choice for tool boxes, storage units, access covers, vehicle compartments and other heavy-duty lid systems.
This model is positioned within our Heavy Duty Gas Struts range, making it more suitable for demanding lid support jobs than light furniture-style gas springs. Where secure mounting, repeated use and consistent lifting force matter, this setup offers a stronger and more application-focused solution.
Product Configuration
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Force Rating: 400N per strut
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Total Support: 800N per pair
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Extended Length: 300mm
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Stroke: Approx. 110mm
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End Fitting: M6 Threaded Ball Joint
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Bracket Type: 4 × Steel L Mounting Brackets
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Supply Format: Pair of 2 gas struts
Where This Heavy Duty Model Is Commonly Used
The 300mm 400N format is typically selected for compact but relatively heavy lids where a short body length is needed without dropping too low on support force.
- Metal storage box lids
- Tool box and site box lids
- Outdoor storage compartments
- Vehicle side lockers and van compartments
- Service covers and access panels
- Workshop cabinet lids
It is especially useful where the lid must open with control and remain supported during loading, inspection or maintenance.
Recommended Lid Size and Weight
This configuration is generally suitable for the following range:
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Recommended lid depth: 400–600mm
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Suitable lid weight (lid only): 40–72kg
Actual performance depends on hinge position, mounting distance, opening angle and the centre of gravity of the lid. Heavier materials such as steel may require more precise bracket positioning.
Important Force Selection Guidance
Getting the correct Newton force is critical for safe and effective lid support.
- If the struts are too weak, the lid may not stay open safely.
- If the struts are too strong, the lid may become difficult to close.
- For medium-heavy lids in compact installations, 300mm 400N is often chosen as a balanced option.
When selecting your model, always consider the lid-only weight, not the total box weight.
Mounting and Installation Notes
This set uses a thread-through M6 ball joint system, which is well suited to more secure heavy-duty mounting compared with lighter clip-on styles.
- Fit one strut on each side of the lid
- Mount the upper bracket around 20–30% from the hinge line
- Fix the lower bracket to the inside wall or structural frame
- Ensure the gas struts remain slightly compressed when the lid is closed
This preload is important because it helps deliver smooth assisted opening from the beginning of the lift movement.
Why the M6 Threaded Ball Joint System Matters
- Provides a tighter and more secure fixing method
- Better suited to metal lids and rigid frame structures
- Helps reduce movement during repeated opening cycles
- Improves long-term installation stability
For heavy-duty external applications, secure attachment points are just as important as the strut force itself.
What You Receive
- 2 × Heavy-duty gas struts
- 4 × L mounting brackets
- M6 threaded ball joint hardware
Customer Experience Benefits
- Helps prevent sudden lid drop
- Makes heavy lids easier to lift and control
- Improves day-to-day usability of boxes and access panels
- Supports a more secure and professional installation result
A Few Important Checks Before Ordering
- Measure the full extended length you need
- Check the lid-only weight rather than the full unit weight
- Confirm there is enough internal clearance for bracket installation
- Choose the force based on real lid resistance, not guesswork
If you are between two force options, the correct choice will depend heavily on your bracket geometry and hinge position.
AUTORCE Support and Dispatch
- Fast UK dispatch
- Quality-checked components
- 30-day returns on unused items
- Responsive customer support
This 300mm 400N heavy duty gas strut pair with 4x L brackets is a strong choice for compact heavy-lid applications where secure fitting, controlled lift support and reliable day-to-day performance are essential.
