Based on the classic Boss Slow Gear, to give you that violin-style swell attack. 

Model: TC Electronic Crescendo
Made: China, recent model
Serial: obscured
Type: auto swell
Power: standard 9v DC negative power supply (not included)
Equivalent new street price (approx): $99aud
Mods: dual lock attached
Accessories: none

Condition notes: used, no major marks. Tested and fully functional.
Overall: very good condition (8/10)