12-17 mm rotor is Teflon-coated aluminum with Teflon hub has 52 smaller holes and 24 larger holes. The larger diameter holes hold 12 or 13 mm tubes and the larger diameter holes hold 16 or 17 mm diameter tubes.
12-13 mm rotor is Teflon-coated aluminum with Teflon hub has 40 smaller diameter holes and 108 larger diameter holes. The smaller holes hold 1.5 or 2ml microcentrifuge tubes and the larger holes hold 12-13 mm test tubes with up to 10ml of fluid volume.
28 mm rotor is Teflon-coated aluminum with Teflon hub has 32 smaller diameter holes and 12 larger diameter holes. The smaller holes hold up to 32 1.5 or 2ml microcentrifuge tubes and the larger holes hold 28 mm test tubes with 40 to 50 ml of fluid volume.