This came with the group of tools/hammers/dollies/B-17 part I bought a few days ago and been wondering exactly what it is for.. I don't see any markings on it, has aluminum handles, you loosen the 3 screws to turn the center piece for adjusting the 3 slots inside. The screw on the side is marked 88/A but not sure if that was originally with it. Any ideas?

It's a die holder. The shutter adjusts around the workpiece.

A die holder with a thread chaser?