1/4" UNF - 28tpi; 0.434" across flats of head; 0.85" thread length.
5/16" UNF - 24tpi; 0.497" across flats of head; 0.94" thread length.
3/8" UNF - 24tpi; 0.559" across flats of head; 1.10" thread length.
7/16" UNF - 20tpi; 0.621" across flats of head; 1.20" thread length.
1/2" UNF - 20tpi; 0.746" across flats of head; 1.20" thread length.
All bolts are partly threaded.
Thread lengths are approximate and may vary.
Bright zinc plated.
Manufactured to BS1768.
Bolt lengths do not include the head.