The barrel-mounted 135mm f4.5 Schneider Xenar. Mounted into a Durst IXTUB recessed enlarger board, and then mounted to a restored Plaubel Peco Junior slightly-recessed lensboard. Just finished putting this together last weekend.
Focuses on my Makiflex Automatics from infinity to several inches, and does not block the mirror when the shutter fires (Yay!). And I can just reach my fingers inside the IXTUB to change the f/stops.
Very useful addition to my Makiflex collection.