A wheel on a fixed point mounted to a 3-sided bracket, the fork (example: |_| ). Varieties include fixed (rigid/one-way/"dumb") and swivel (360° rotation/"smart") casters.
Colson Casters
Unsolicited advice: Don't skimp on the quality of your casters. Always buy the best you can afford. In the long run, cheap casters are no bargain.
See also v-groove and zero throw caster, and the thread http://www.controlbooth.com/forums/scenery-props-rigging/10245-what-caster-should-i-buy.html .
Colson Casters
Unsolicited advice: Don't skimp on the quality of your casters. Always buy the best you can afford. In the long run, cheap casters are no bargain.
See also v-groove and zero throw caster, and the thread http://www.controlbooth.com/forums/scenery-props-rigging/10245-what-caster-should-i-buy.html .