Advice please unusual battery connector

[Adam]

I have been asked to find a battery for this sensor pocket watch. When I opened it up I recognized the module as the same as one in the Sensor Tritium watch. Problem is the big metal disk with small bar and what looks to be a clamp. The watch didnt come with a battery so I dont know what its meant to have and whether the bar is of any importance. My other sensor takes an AG3 so I tried one of those and it works fine.
Has anybody seen this set up before? could I just remove the bar?

thanks

Adam

[Adam]

Doesnt anybody have any ideas. Do you reckon I can just remove the bar?

Adam