Bolt cylinder head, Norton early twins (set4)

Bolt cylinder head, Norton early twins (set of 4). Outer head bolt by spark plugs, 4 required. Pre 750 head. These fit iron heads and alloy heads. The bolt heads are 3/8 in BSF and  were reduced in head size after early Commandos. Atlas heads have a different size bolt.
Original Norton part numbers:
D12/972; T2096; 060401; 06-0401 - cylinder head and barrel bolt (long) 3/8"