Blue Epoxy Coated Steel Wire Test Tube Rack, 24 Holes, Outer Diameter permitted of tubes 15-16 mm or less, 4 X 6 Format Rack measures 5" x 3.5" x 2.5" Holds a total of 24 test tubes. Coated steel wire racks are chemical and corrosion resistant. Coating provides a protective and smooth coat that is impervious to weak acids , bases and salts. With stands temperatures up to 121 degrees C ( 249.8 degrees F)