Krisbach007

I have found these 2 bricks together in my attic...probably from the 80's as thats the era i was born in... The round one in the back, i think is to turn on the lights of a fire- or police car, so i thought the other one would be a battery pack as it is far heavier then a regular brick. But i don't seem to get it to open...what are you're thoughts? Thanks in advance... https://drive.google.com/file/d/1xyKylIpc2ZW02qsVNtDJc7AvCO-mTzWl/view?usp=sharing