This self-locking hex nut with a nylon insert is made of steel with an electro-galvanized finish, making it suitable for indoor use or applications with very mild exposure. The nut is grade 6 and is designed to be paired with bolts and screws of grade 6.8 or lower. It features British Standard Whitworth (BSW) threading. These self-locking hex nuts are not standardized, so dimensions may vary slightly depending on availability. Whitworth threading (BSW/BSF) is no longer recommended internationally; for new construction, we recommend using metric (M/MF/MEF) or Unified (UNC/UNF) threading instead.