Used Vintage Casio VL - Tone VL-1 Electronic Musical Calculator ( Mini Synthesizer Drum Machine Keyboard ) in a very good cosmetic condition and working order . Uses 4 AA batteries ( not included ) The battery compartment is clean. The only issue is that one of the battery terminals accidentally got heated making a little area around it a bit burnt (check photos 6 & 7) but is not having any effects. All functions work fine .