A twist lock receptacle will prevent accidentally connecting non-POS items like refrigerators, heat lamps, drink machines, etc. to the POS circuit. If this should happen the voltage surges and transients caused by this equipment will corrupt POS data, effect terminal operation and may even damage the POS hardware. The other advantage of a twist lock is it reduces the probability of accidentally disconnection POS hardware when items are moved under the counter or around the receptacles.