Metal on a plywood base.
These are metal printing plates mounted onto plywood bases.
Used to print fusewire cards for Wylex fuse wire.
Vales of wire on these cards is 5 amp, 15 amp, 30 amp.
Unusually, the wire gauge is also specified, 34 SWG, 25 SWG and 22 SWG.
Wylex Tinned Copper Fuse Wire.
Fuse Wire For Wylex Rewirable Fuse Control Units.