The Hoyt Model BT-2A is a vintage battery loadmaster tester designed for 6 and 12 volt batteries. It is a dynamic tester used for testing the functionality and capacity of automotive batteries. What's my dad's been sitting in the toolbox for over 40 years time to go it does work look at all the pictures. It's all there the glass does have I'll call it three cracks one that comes from the screw hole at the bottom and goes off to the 4:00 position, another one that goes from the screw hole and goes off toward the 8:00 position and then it seems from that 8:00 position a crack runs up to the 10:00 position but the unit is fully functional