Dimensions taken from my Dad's WW2 RCN discs:
Brown fibre discs as seen here
Measured diameter 1.38 inches
Thickness .070 inches
Lanyard hole diameter .175 inches with an edge distance of .200 inches to centre of hole
Weight unknown due to no scale
Also have an elongated octagonal ID disc which is more of a khaki colour
Thickness .060 inches
Height 1.325 inches
Width 1.540 inches
Lanyard hole diameters (2) on ends of "disc": .175 inches with an edge distance of .250 inches to centre of hole
Upper/lower lines of the octagon .600 inches
All other lines .550 inches.