... : flat head ,countersunk head, round body, hex body, open end, closed end, body with ribben, body with groove Riveting nutwe use cold ... : flat head ,countersunk head, round body, hex body, open end, closed end, body with ribben, body with groove and so on . also ... 3/16,5/16. material: steel, stainless steel, brass,aluminium. Reduced Head Rivet nut