This polypropylene rack is just the right size for serum vials (10-13mm diameter), RIA vials and T3/T4 reaction vials (13-16 & 16-20 mm diameter).  Long-lasting and corrosion-resistant, these racks fit most water baths for elevated temperature incubations.  Top shelf is 1-5/8".  End plates have handles.  Steam autoclavable at 250°F (121°C).