The Molecular Property Spectrometer™ (MPS™) Flammable Gas Sensor Evaluation Unit is a user-friendly sensor system developed for assessing flammable gas detection performance. The evaluation system is shown in Figure 1. The sensor is 20.0 ø x 16.6 mm with 1.52 mm diameter connector pins and connects to a provided evaluation PCB for communication with a PC (USB) or breakout to individual sensor signals (optional 5-wire harness). The sensor contains the MPS sensing element, environmental sensor, microprocessor, and supporting electronics. A quarter-turn plastic gas mask and housing is included to provide a sealed headspace above the sensor for test gas delivery.