3 3/8" X 4 1/4" (85mm X 108mm)

No markings

Picture courtesy Bob Berry

3 3/8" X 4 1/4" (85mm X 108mm)

No markings (base view)

Picture courtesy Bob Berry

3 1/4" X 4 1/2" (82mm X 114mm)

No markings (base view)

Picture courtesy Byron Smith