Classification of compressor parts: identifiable components of refrigerating and air conditioning machinery qualify for Item 29A(3) duty treatment. Where components of compressors for refrigerating and air conditioning appliances and machinery are identifiable as specific parts of those compressors, they are classifiable under the tariff provision corresponding to Item 29A(3) and subject to the prescribed excise duty treatment; the Board endorsed the Tariff Conference view rejecting the audit contention that such parts are general purpose and outside that tariff coverage.