These flame-sealed cells contain 100 Torr of >99.9% pure propane (C₃H₈) at room temperature. They are used for calibration of tunable lasers around 2500-3375 cm^-1 (2950-4000 nm). Propane exhibits many strong and well characterized absorption lines in the C-H stretch region, more than methane or ethane, and over a wider frequency range. However, the line density may be too high to be useful in near the center of the absorption feature for some experimental setups.

The quartz cell body is cylindrical in shape; outer diameter 10 mm; length 75 mm. The tipoff stem is centered on the cell, protruding not more than 8 mm from the cell body. Windows are angled 11° off of normal and have a 2° interior wedge to prevent back-reflection and etalon effects.