 The lowest variant is the four-seat/one-arm design, and the capacities increase to 8 seat, 16 seat, 32 seat and 40 seat designs, all utilizing two arms.For two-arm models, the swings can operate individually or simultaneously (although in opposite directions) and are propelled by compressed air, provided by Ingersoll Rand or Sullair compressors.These compressors disperse air into tanks located within the arms, the movement triggering actuators and cables to produce the motion.