The SM-20 is a small, compact and simple rhythm machine that provides up to 20 rhythm patterns with 15 basic electronic drum sounds. It is primarily used as a music teaching device (like a metronome) or for providing (limited) accompaniment. It has a built-in 25 watt speaker, electronic conductor and metronome for practicing. There is also an instrument input jack that will feed the 25 watt speaker. However it can be used in music production if you really wanted to, but the limited sounds and rhythms are not very inspiring.
Images from Music Machines.