WIROX coating of these spax 3.5 x 20mm woodscrews offers 10 times higher corrosion protection in the neutral salt-spray fog test than is required by standard for conventional yellow zinc coating, and has considerably higher surface hardness.
Ideal for outdoor use in structures such as e.g. carports or pergolas, which are not directly exposed to the elements.
The WIROX coating is free from chromium-VI, so environmentally friendly
Partial thread: firm tightening of the upper wood layer
T-Star plus (or Torx) gives secure bit grip, no cam-out effect and optimal force transmission (T20 bit size)
Drilling point allows screwing in without pre-drilling (wood-dependent), reduces splitting as square end displaces the fibres
Ground serrations up to the point for quick and secure fastening
Flush countersinking head so mills in wood and stops on metal
3.5mm (size 6)