Ken, it is a ball leveler. The lever on the side -- look at the picture @ B&H -- clamps and unclamps the head.
My 138s (long story, I have two) are similar but have a handle that screws in to clamp the ball. Set up is very fast and easy. I've had to lubricate the clamp's threads with graphite powder to make secure clamping easy. Here's a 138: http://www.ebay.com/itm/Manfrotto-Bo...-/330577540001
I share your distaste for balls -- I find ball heads nearly impossible to use -- but with a claw ball plus a 3-axis head the ball serves only to make the 3-axis head's pan axis vertical. After that's done, the 3-axis head is used normally.
Cheers,
Dan
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