These disposable culture tubes can be color coded to easily identify lab experiments. They come in optically clear polystyrene or autoclavable polypropylene. Colored polyethylene plug caps are available with dual flange seals or a ribbed design. The tubes measure 12 x 75 mm with round bottoms. Colored polyethylene plug caps are available with dual flange seals or a ribbed design. SMPT400-34 tubes are all aligned and packaged in boxes of 250, 1000 per case in order to fit into stainless steel dispensers (Sold Separately)