Polyfoam racks for PCR, microtubes and centrifuge tubes Eliminate expensive plastic floating racks with economical polyfoam floating racks. Easy to use in waterbaths or beakers. Inscriptions with  Identi-Marker  pens may be made for quick identification. Unique Features Economical Easy to use Non-absorbent Sizing Circle - 83 x 9.5mm (3-1/4 x 1/8") Octagon - 83 x 6.4mm (3-1/4 x 1/4") Triangle - 86 x 13mm (3-3/8 x 1/2")