A nylon insert on top of the nut creates a prevailing torque, resists loosening and allows reuse after several removals without significant performance loss.
Also available in thin series. Colour coding is also helpful, Blue for Metric, White for Imperial, Off White for Metric Fine (not 100% reliable, but a fairly good indicator as to thread pitch).
Available in UNC 4-40″ to 3/16″ to 2″, UNF 8-36″ to 3/16″ to 2″.
BSW :- 1/2″
Metric Coarse M3 to M42, Metric Fine M8 to M30, Metric Galvanised M8 to M24.