... >Material:C1022 harden 2>surface: galvanized 3>dia:3.5,3.9,4.2,4.8mm countersunk phillips self drilling screws (factory ... screws, drilling screws**Material: carbon steel C1022**head type: bugle head, Hexagonal head, countersunk head, wafer head, flange head, flat head, truss head, etc.**Feature: zinc coated (white, blue ...