Wafer head self drilling screw

Wafer head self drilling screws are also called modified truss head self drilling screws（metal lath screw, k-lath screw) with large head and low profile which provides extra surface area to attach wire lath to metal studs. 

Material :Case hardened steel C 1018,C 1022 with heat-treated
Stainless steel 304/316/410.
Surface:zinc plated, H.D.G, Black phosphated.
Surface hardness:The minimum surface hardness of self drilling screws after heat treatment shall be 530 HV.
Core hardness:The core hardness after heat treatment shall be 320 HV to 400 HV.
Tolerance: Grade A conforming to ISO 4759-1.