The friction-fit polystyrene rack slides smoothly across the benchtop and snugly fits tubes from 27.5 to 29.0 mm in diameter. The autoclavable, epoxy-coated steel wire rack provides more friction with the benchtop for more secure positioning. Both racks hold conical- or round-bottom tubes. Friction-fit rack measures 92 mm dia x 30 mm H and sold in pack of 5. Coated wire rack is not recommended for cleaning in autoclave, measures 90 x 67 x 67 mm and sold as eaches.