Gasket, cylinder head, Norton twin 500-650 no spigots, Hallite

Hallite cylinder head gasket for Norton twins 500, 600, 650 without spigot on barrel (flat head), made in UK.  Hallite type wire reinforced head gasket, no flame rings, accurately made. ID approx 69mm.
Original part numbers:
25324; 067920 - cylinder head gasket