Draeger equivalent 1.1% vol. Propane 50% Lel (C3H8) span gas cylinder used to calibrate Draeger gas detection equipment with propane 50% lel gas sensors. Fully compatible with Draeger gas detectors requiring 1.1% vol. propane 50% lel with balance air. Precision blended and inspected to industry standards, National Institute of Standards and Technology (NIST) traceable and certified.