This is a Compur Electronic No. 1 shutter. It is in great shape and very accurate. Includes a retaining ring. Batteries are readily available through Amazon (https://www.amazon.com/Exell-Battery...+A21PX+battery). You can also use three AAA batteries in a holder to supply power. I will included a holder so you can fabricate a battery holder for AAA batteries. The front and rear threads are identical to Copal No. 1 shutters. The aperture scale is correct for a 180mm, f/5.6 lens. Asking $50 including Paypal and CONUS shipping.