This is a wow factor for hotels! The RF1600 implements an impressive wave over RF card technology. Not only this cool but it is also functional. Since there is no slot to slide in a card, that means added protection for the internal components. Perfect for ocean front properties with corrosive salt air. Designed with unique electronics, the RF1600 will operate for more than 1 year with ordinary 4 AA batteries. Includes an emergency metal override key feature.