BSF meaning British Standard Fine, an old style British thread. Often used on vintage British automobiles and machinery as its fine thread is preferred. Available in steel and stainless steel although stainless can now be difficult to source.
New stock In 2021 we were lucky enough to purchase 8 tonnes of British steel fasteners. Approached by a farmer’s family in Cheshire, and
We are often asked what size hex Allen key wrench will fit a certain socket screw. Below is a conversion chart to help: Metric Socket