Vintage AM FM Receiver Air PB/WB Radio Model ST-825

Vintage AM FM Receiver Air PB/WB Radio Model ST-825. 10" tall, 6 1/2" wide, and 3 1/2" deep. Battery compartment not tested. I have video of the FM and AM working but can't upload it on here. I'm not sure what the AIR P B W B is for or how to test it but it crackled when I turned the tuning knob like the radio does when turning it to a new music station. One snap strap that helps hold the back compartment shut is missing, see photos.