Headshell
A headshell is a head piece designed to be attached to the end of a turntable's or record player's tonearm, which holds the cartridge.[1] Standard catridges are secured to the headshell by a couple of 2.5 mm bolts spaced 1/2" apart. Older, non-metric cartridges used #2 (3/32") bolts.[2]
Some headshells are designed to allow variable weights to be attached. For example, the H4-S Stanton headshell comes with 2g and 4g screw-in weights. Extra weight can be useful to prevent skipping if the DJ is scratching the record.