Thermometers or bleed tubes are angled into the bottom of a flask A vacuum-tight seal is created with the open top compression cap and FKM o-ring to allow adjustable immersion of thermometers Cap is suitable for use to 150 °C Supplied complete with one size 010 FKM o-ring and one 410119 cap Manufactured from 33 expansion, low extractable borosilicate glass conforming to USP Type I and ASTM E438, Type I, Class A requirements