Speeds up to 300 feet/minute. Lifting distances up to 300 feet. Self supporting tower: a structure consisting of four corner angles rigidly braced that will support the dumbwaiter and avoid imposing loads except at the base. Power operated doors and gates. The doors and gates can be motorized so that they can automatically open and close. Variable frequency and vector based drive systems. Security systems: Key locks Keypads Interfaces to external security systems