Chart’s Dura-Cyl® product is a low, medium or high pressure liquid nitrogen cylinder (22-350 psig/15.9-24.1 bar). The Dura-Cyl liquid nitrogen cylinder provides the longest holding time, lowest evaporation rate, highest gas-withdrawal rate and best life-cycle cost. Dura-Cyl LP models feature the "sight gauge" liquid globe valve with an extended stem for less ice build-up on the handle for easier operation. MCR models have a combination pressure control regulator with an exclusive, calibrated micrometer adjusting screw. (MP & HP models only) LCCM models have an integral mounted combination pressure control regulator, isolation valve and a calibrated dome control knob. (MP & HP models only) (SB-Square Bottom, RB-Round Bottom)