5/16″ UNF x 2-3/4″ Hex

A 1/4 BSF hexagon set bolt (threaded up to head)Under head dimension: 1". Standard hexagon size (.445" A/F)Head machined flat (no markings).

A 1/4 BSF hexagon bolt (part threaded)Under head dimension: 2". Thread length: 9/16". Standard hexagon size (.445" A/F)Head machined flat (no markings).

A 1/4 BSF hexagon set bolt (threaded up to head)Under head dimension: 3/4". Standard hexagon size (.445" A/F)Head machined flat (no markings).

A 5/16 BSF hexagon bolt (part threaded)Under head dimension: 3-3/4".Thread length: 5/8" Standard hexagon size (.525" A/F)Head machined flat (no markings).