49 C.F.R. § 173.201
(b) The following combination packagings are authorized:
Outer packagings: Steel drum: 1A1 or 1A2 Aluminum drum: 1B1 or 1B2 Metal drum other than steel or aluminum: 1N1 or 1N2 Plywood drum: 1D Fiber drum: 1G Plastic drum: 1H1 or 1H2 Steel jerrican: 3A1 or 3A2 Plastic jerrican: 3H1 or 3H2 Aluminum jerrican: 3B1 or 3B2 Steel box: 4A Aluminum box: 4B Natural wood box: 4C1 or 4C2 Plywood box: 4D Reconstituted wood box: 4F Fiberboard box: 4G Expanded plastic box: 4H1 Solid plastic box: 4H2 Metal box other than steel or aluminum: 4N Inner packagings: Glass or earthenware receptacles Plastic receptacles Metal receptacles Glass ampoules
(c) Except for transportation by passenger aircraft, the following single packagings are authorized:
Steel drum: 1A1 or 1A2 Aluminum drum: 1B1 or 1B2 Metal drum other than steel, or aluminum: 1N1 or 1N2 Plastic drum: 1H1 or 1H2 Steel jerrican: 3A1 or 3A2 Plastic jerrican: 3H1 or 3H2 Aluminum jerrican: 3B1 or 3B2 Plastic receptacle in steel, aluminum, fiber or plastic drum: 6HA1, 6HB1, 6HG1, 6HH1 Plastic receptacle in steel, aluminum, wooden, plywood or fiberboard box: 6HA2, 6HB2, 6HC, 6HD2 or 6HG2 Glass, porcelain or stoneware in steel, aluminum or fiber drum: 6PA1, 6PB1 or 6PG1 Glass, porcelain or stoneware in steel, aluminum, wooden or fiberboard box: 6PA2, 6PB2, 6PC or 6PG2 Glass, porcelain or stoneware in solid or expanded plastic packaging: 6PH1 or 6PH2 Cylinders, specification or UN standard, as prescribed for any compressed gas, except 3HT and those prescribed for acetylene.
[Amdt. 173-224, 55 FR 52634, Dec. 21, 1990, as amended by Amdt. 173-241, 59 FR 67518, Dec. 29, 1994; Amdt. 173-261, 62 FR 24734, May 6, 1997; 71 FR 33880, June 12, 2006; 78 FR 1089, Jan. 7, 2013]