SAFE-T-FILL Micro Hematocrit tubes are 100% plastic to ensure safe and accurate micro hematocrit determinations. Designed with the same capillary action properties as glass, our micro hematocrit tubes fill quickly without the risk of breakage. The tubes are available plain or heparinized and are color-coded for easy identification. A red band indicates heparinization; blue indicates plain. Heparinized tubes are evenly coated with either sodium or ammonium heparin to prevent clotting. Ammonium heparin does not interfere with sodium identifications. The tubes are packaged in plastic vials with re-closable caps for cleanliness.