It's a phaser... but wait, there's more. There's two stages, and you can run one or both. The second phase has a separate mini rate control. There's a lot of fun to be had, it has a plenty of 80s attitude.

Model: Aria PS-10 Phase Shifter
Made: Japan, 1980s approx (serial 30401726)
Type: phaser
Power: standard 9v negative supply or 9v battery (not included)
Switching: buffered bypass
Equivalent new street price (approx): n/a
Mods: none
Accessories: no box or manual
Condition notes: used, few minor marks, fully functional. Overall: very good condition