Fixing and buying guide
ST400500 Ulti-mate II Professional Woodscrew PoziSquare Double Csk Z&Y - (8g) 4mm X 50mm - 800 Tub
What this screw is for
These woodscrews are ideal for general carpentry, joinery, hinge installation, and fitting work where a countersunk finish is required. The 50mm length penetrates effectively into hardwoods and softwoods, whilst the 8g gauge provides strong holding power without excessive splitting risk. The absence of ribs on this size makes them particularly suitable for use with hinges and other hardware fittings where a clean, flush finish matters.
- General carpentry and joinery applications
- Hinge and fitting installation
- Countersunk fastening where flush finish is needed
- Internal and external use (zinc yellow plated)
Key features and compatibility
The PoziSquare recess is self-centering and compatible with both PH (Phillips) and PZ (Pozidriv) drivers, giving you flexibility in your tool choice. The anti-camout technology ensures stick-fit and stable driving, reducing the risk of bit slip and screw damage. The reinforced double angle head self countersinks as you drive, eliminating the need for pre-drilling a countersink in most softwoods. The quick start point allows rapid starting with minimum force, reducing operator fatigue on larger jobs.
- PoziSquare recess works with PH and PZ drivers
- Anti-camout design prevents bit slip and stick-fit failure
- Self countersinking double angle head
- Quick start point for fast, low-force driving
- Slotted shank reduces wood splitting
Pack contents and sizing
This product is supplied as an 800-piece tub of 8g x 50mm screws. The 4mm gauge is a standard size for general woodwork, and the 50mm length is suitable for fastening timbers of 25mm to 35mm thickness where you require good penetration into the substrate. Check your specific application requirements before ordering to ensure this length and gauge are appropriate for your project.
- 800 screws per tub
- 8g gauge x 50mm length
- Suitable for 25-35mm timber fastening
- Zinc yellow plated for corrosion resistance
Pre-installation checks
Before use, ensure you have a compatible driver bit (PH or PZ) in good condition. For hardwoods or dense timbers, consider pre-drilling a pilot hole to reduce splitting risk, even with the slotted shank design. Check that the 50mm length is appropriate for your substrate thickness and that you have adequate clearance beneath the workpiece. Store the tub in a dry environment to maintain the zinc yellow plating integrity.
- Use PH or PZ driver bits in good condition
- Pre-drill pilot holes in hardwoods if needed
- Verify 50mm length suits your timber thickness
- Keep tub dry to preserve corrosion resistance