Hex Head 8 gauge-18 threads per inch x 12mm long screw full thread with seal, class 4 coating
Hex Head screws without seals are for general fastening to metal where a water tight seal is required.
The Class 4 corrosion protection system meets the requirements of ISO 9223 Category 4 (Outdoor application for moderate and severe environments).
AS 3566.2 (Self drilling screws for the building & construction industries) specifies the corrosion protection systems required on screw fasteners Classes 1, 2, 3 & 4 where Class 1 is intended for indoor application and Class 4 for environments up to and including ISO 9223 Category 4 (Severe industrial and severe marine environments).
