This is a new VARIABLE SPEED CONTROL POTENTIOMETER for a GREENLEE 6810 Cable Feeder!  If your Ultra Feeder is no longer able to vary the speed of the motors, then this could be one of the possible reasons!

 If you don't need it now, it's good to have one for a back up!  They are not usually in stock at your local Greenlee Dealer! it is part# 67 in the drawing. You would need to reuse your old knob and wires. Just solder them or use a push terminal to connect them to this new unit!