1. The Revision Application dated 12.3.1980 against order No. 2144/77 dated 21.8.1979 of the Appellate Collector of Customs, Calcutta has been transferred to the Tribunal by the Government of India, for disposal under the provisions of Sec. 131B(2) of the Customs Act, 1962. A consignment of Packing Type G8F2 without Flange and Guide bushing, Packing rings of PTFe with back-up rings, packing cups of Stainless steel 13 mm rods being spares for Synthesis Gas Compressor was assessed to duty under T.I. 84.64 under B/E No. DI 566 dated 25.9.1977. A claim for refund on the grounds that the goods were assessable under heading 84.11(1) instead of 84.64 was rejected by the Asstt. Collector of Customs because the catalogue and past evidence, called for, was not furnished. Their appeal that these packings are essential parts of gas compressor classifiable under heading 84.11 applicable to the compressor was also rejected, on the ground that the "Technical note submitted with the appeal clarified that these are for lubricating valve on the lubricating lines to lubricate the moving parts of compressor. The general principle that recognizable specialized parts of the goods falling in heading