#roller.wheel  a small wheel without spokes (as on a roller skate)
  supertype:  #wheel  a simple machine consisting of a circular frame with spokes (or a solid disc) that can rotate on a shaft or axle (as in vehicles or other machines)
  part of:  #roller_skate
  subtype:  #caster.roller__castor  a pivoting roller attached to the bottom of furniture or trucks or portable machines to make them movable

No statement uses or specializes #roller.wheel; click here to add one.