This regulator is usable by all Alco-Sensor type instruments for accuracy checks and calibration adjustments. Some Alco-Sensor type instruments, like the Alco-Sensor FST, will not auto sample with the low volume 1.5 liters per minute (lpm) regulator. A manual sample will need to be performed. Each regulator comes standard with its designated LPM barb attached. An additional barb purchase is not necessary. This regulator can be converted back and forth between the high and low volumes by purchasing a different LPM Regulator Barb.