An adapter for securing a cable to a housing has a flange that is attachable to the housing and a plurality of concentric cable ports connected to the flange. Each cable port has a side wall. The side wall of each cable port overlaps a side wall of an adjacent one of the plurality of cable ports. Each cable port has a respective diameter and a respective height with respect to the flange, and the heights of the cable ports increase monotonically from the cable port having the largest diameter to the cable port having the smallest diameter. Each cable port other than the cable port having the smallest diameter has a flat surface at a distal end opposite the flange. Each pair of successive cable ports differ from each other in height by a constant amount that is at least a thickness of a blade used to cut unused ones of the plurality of cable ports from the adapter. Each cable port may have a ledge proximate to the distal end. The ledge of an inner one of an adjacent pair of cable ports within the plurality of cable ports is located at the same height as the flat surface at the distal end of the outer one of the pair of cable ports. The adapter may be formed from a single piece of material, adjacent cable ports connected to each other.