Brass plated cover plate includes slotted locking mechanism Opens with simple turn of a flathead screwdriver or coin Cover plate consists of 7'' 18cm O.D. brass outer ring and hinged brass cap Heavy duty steel sleeve receives 3'' to 3 12'' 7.6 to 8.9cm upright and is 9 14'' 23cm deep 1'' 2.5cm clearance required between top of floor and sleeve