Used for a positive identification of the type and pitch (windings) of threads used on bolts or nuts. Whitworth threads (BSW; Britisch Standard Whitworth) is an imperial standard developed in 1841 and became the British Standard. Today you may find this thread on many older (but not all) pre-1970 British motorcycles and cars. - Threads: Whitworth - Degree: 55 degrees - Number of blades: 28 - Pitch: 4; 4.5; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 16; 18; 19; 20; 22; 24; 25; 26; 28; 30; 32; 36; 40; 48; 60; 62