Socket Screws - Countersunk - BSW

BSW (British Standard Whitworth) is an imperial coarse thread first used in standard production by Joseph Whitworth during the industrial revolution. Whilst it is still used in engineering applications all across the world it is less common in the UK where metric threads have generally taken over.

A countersunk head is usually used when no part of the fastener head is required to be protruding above the level of the substrate. Countersunk heads can also be recessed and filled over if a hidden fixing is required. Usually abbreviated to CSK.