Samplesphere has released Daf, a free virtual instrument for Windows featuring a Persian ethnic percussion drum.
The Daf is a Persian frame drum with small metal rings attached to the inner circumference of the frame. All you need to know about using this Daf is in the help incorporated into the interface (take a look at the pictures).
Example MIDI files in various time signatures are included.
Daf is available as a 32-bit VST instrument for Windows (FL Studio 64-bit will load it via jBridge).
More information: Samplesphere