SCHNEIDER Xenar 135mm f4.5 large format lens 5x4" compur shutter REF:2268
I di not realise Xenar's cold be like this, so i may be wrong. other aperture show markings from f6.3 upwards to f25. 13.5cm (135mm) f4.5 large format lens, most likely designed for 9x12cm but will cover 5x4" once stopped down.