This rack accommodates 96 x 0.5 mL microcentrifuge tubes on one side, or 96 x 1.5 - 2.0mL microcentrifuge tubes on the other. The rack is arranged in the standard 8 x 12 array. It features a handy snap-in-place lid, and easy to grasp tabs on each end of the rack. Grid lines are molded on the side of the rack that accommodates the smaller tubes making it easier to see the wells. Raised rings are molded on the other side of the rack making it easier to replace the 1.5 - 2.0 mL tubes from those wells.