locking rod 255 on an opposite side of piston 251 from clamping finger 233 bolt 331 has a metallic sensor flag 333 attached to a leading end thereof by a circlip or the like bolt 331 and the attached flag 333 can be longitudinally positioned at various locations within a cavity 335 inside locking rod 255 the location of flag 333 is sensed by sensors 337 of a proximity switch in order for the proximity switch to determine the stroke position of locking rod 255 and the associated piston and clamping finger which longitudinally advance and retract therewith accordingly bolt 331 and the internal cavity location of flag 333 serve to provide a compactly packaged and protected location while providing essentially infinite adjustment of the sensing flag with the adjustment being accessible from outside of the clamp after the clamp has been assembled and installed in the manufacturing plant an air pressure port or inlet 351 for clamping piston retraction a port or inlet 353 for loading unloading and piston advancement and a constant air port or inlet 355 for retracting lock 252 are all present on the bottom end of housing 223 a single pneumatic supply line is connected to a tee supply.