Briggs Mystery Tool????

I picked up a pickup truck load of parts for $50 that were unsold from the closing auction of a small engine shop.


In the mix I found 2 of the things I have pictured below. I think they're some kind of tool from Briggs & Stratton. I was wondering if anyone could tell me what they are for and how to use them.














The knob screws in and out and the little pins you see protruding into the opening move parallel to the plane of the circular whole.