They seem to be made of bakelite.
Are they Jowett? If so, and any Club member wants them, they are gratis except for the postage.
Send me a P.M. and include your address.
Tony.
Photo a bit fuzzy.
Left one dimensions 3 and 7/8" x 2 and a half" x 9/32" small holes 11/16"
large holes 30 mm
Right:- 3 and 15/16" x 2 and 9/16" x 7/16" small holes 11/16"