2 3/4" X 3 3/4" (71mm X 94mm)

(dome incuse) C P R

{Pittsburg High Voltage}

Picture courtesy Bob Berry

2 5/8" X 3 3/4" (67mm X 95mm)

(skirt inkstsmp)

{Canadian Porcelain}

Picture courtesy Barrett Nicpon

2 5/8" X 3 3/4" (67mm X 95mm)

No markings

{Canadian Porcelain}

Picture courtesy Barrett Nicpon

2 5/8" X 3 3/4" (67mm X 95mm)

No markings

{Canadian Porcelain}

Picture courtesy Barrett Nicpon

2 3/4" X 3 3/4" (67mm X 95mm)

(dome incuse) C.N.R.

Picture courtesy Barrett Nicpon

2 3/4" X 3 7/8" (67mm X 95mm)

(dome inkstamp) C.P.R.

Picture courtesy Bob Berry

2 3/4" X 3 7/8" (67mm X 95mm)

(dome inkstamp) T.& N.O.R.Y.

Picture courtesy Bob Berry

2 7/8" X 3 3/4" (70mm X 92mm)

(dome inkstamp) C.N.R.

Picture courtesy Bob Scafe