Rack kit for 18 mm OD collection tubes, 24 tube capacity. Up to 9 racks can be used in each FRC-40 or LH-40. Use 228-25317-91 for 18 x 165mm, 32 mL glass tubes; 228-25316-91 for 18 x 105mm, 20 mL glass tubes; 228-25320-91 18 x 150mm, 25mL polypropylene tubes. 15mL polypropylene tubes EPPE-0030122151 can also be used.