13 Notes: C C# D D# E F F# G G# A A# B C Easy To Pump, Multi-Fold Bellows High Quality Brass Reeds This is a handmade instrument and minor scratches/chips might be present. Long Sustain, Checked For Leaks A shruti box (sruti box or surpeti) is an instrument, originating from the Indian subcontinent that traditionally works on a system of bellows. It is similar to a harmonium and is used to provide a drone in a practice session or concert of Indian classical music.The shruti box is also used in classical singing.