S4 Rhythm Composer is a simple, elegant, and free drum machine for the iPad that offers a 64-step sequencer and 10 PCM sound files (Kick, Snare, Tom1, Tom2, Tom3, HandClap, HHopen, HHclose, Ride, Crash) to let users build drum tracks and beat loops. Users can also add effects to their drum patterns and then export the audio as a loop.