The C&H Precision plates are designed, manufactured and shipped from their small family owned business in Coastal Georgia. Each plate is precision machined to the tightest tolerances on HAAS CNC machines and each plate goes through multiple quality checks before shipping to customers. Most of the plates feature a patented stainless steel T-Nut which provide an industry leading six to seven threads of engagement. Since all the mounting hardware is replaceable, if any mounting hardware is damaged it can be replaced without replacing the entire plate.Features : For GLOCK 17, 19, 20, 21, 22, 23, 34, 35, 40, 41, 45, 47 Material: Plates are made from 6061 aluminum Finish: MIL-SPEC Type III Hard Anodized Replaceable 416 Stainless Steel T-Posts for maximum thread engagement Includes (1) Optic Plate, (2) M3 Plate Mounting Screws, (2) 4-40 Mounting Screws, (2) 416 SS T-Nuts