Manufacture Size: Ligne 21 8/16 or 48.500mm.
Glass Pocket Watch Crystal 20 1/16 45.4mm Mi-Chevee USA Railroad C20-7 NOS Read!
Manufacture Size: Ligne 20 1/16 or 45.257mm. The crystal must be high enough to clear the hands, but low enough to fit under the cover. The crystal used for this type is very thin and fragile so it should not be pressed in the middle when fitting, or even to close the door.Thicker hunter pocket watches generally use crystals 5 or 6.