Curb adapters are special units used together with roof curbs. Often when heating, ventilating or air conditioning equipment is being replaced, the new unit does not identically match the existing roof curb. A curb adapter is then custom made to meet the new unit’s specifications to correctly match the existing roof curb. L/Arden manufactures two different styles of curb adapters: the curb reducing adapter (CA-R) and the curb increasing adapter (CA-I).