Roto toms - Roto toms began life as a cheap version of the orchestral tympani and/or marching quads for use in schools etc where size and expense made the real things impossible. They use a single thin head stretched over a cast aluminum hoop rather than a shell. They are called "Roto toms" as the tension on the head (and therefore the pitch) can be altered simply by rotating the drum on its support rod. Roto Toms have since become a fairly popular addition to many drums kits or sets, partially because of their unique sound which adds a useful texture to the kits repertoire, but also because they are tunable to a distinct tone which can be useful in some songs. They can either be played on a stand for concerts or with a harness for marching.