1902 American Eagle Cartridge Counter
As above, with "Powell Indicating Device" added to left grip. Slotted left grip, with a numbered window that allows visual access to number or rounds remaining in special "indicator magazines". There were 50 Lugers altered in this way at the request of U.S. Board of Ordinance, for U.S. Army evaluation. Serial numbers are 22401-22450. Be especially wary of fakes!