The155mm f7 StarFire EDFS on 900GTO mount with 2.7" Prime Focus Field Flattener with Camera Adapter for Pentax 6 x 7 cm Camera (67PF56), 2.7" Prime Focus Field Flattener with Camera Adapter for Pentax 6 x 7 cm Camera (67PF56) and Pentax 6X7 medium format camera.