Contax Real-Time Winder W-3 d-dx the undivided top compartment is

the undivided top compartment is about the same

clean diaphragm

lots of things

so there's an extra step there that may be unfamiliar if you're used to coupled rangefinders

An infrared film with sensitivity up to 820nm

Contax Real-Time Winder W-3 d-dx the undivided top compartment isThe Contax Real Time Winder W 3 is designed for use with the Contax RTS II Quartz camera (sold separately). It provides a secure handgrip, a vertical shutter release button, and up to 3fps continuous operation. In excellent condition, with minor cosmetic wear, one small missing trim piece from the area around the vertical shutter release. Good working order.