20b.br1
Brass, deep rim for GRB. 31/32'' overall diameter | 20b.br2
Brass, standard rim for outfits, 3/4'' overall diameter | 20b.nb
Steel face, enamelled blue | 20b.re
As above but red |
20b.ni
Nickel-plated, pre-war stamping | 20b.br
Plain brass casting, post-war | 20b.bk
One-part alloy casting, painted black (Korean) | 20b.bm
One-part alloy casting, matt brass plated, boss attached |
20b.bm1
One-part alloy casting, matt brass plated including boss | 20b.zn
One-part alloy casting, zinc | 20b.ir
One-part alloy casting, iridescent |