The Det-Tronics family of catalytic combustible gas sensors provide unmatched flammable gas detection performance in harsh environments and challenging conditions. The heart of the catalytic sensor consists of a pair of computer matched pellistors (beads) that provide identical electrical resistance in clean air. When flammable gas is present, the active bead catalyzes the combustible gas molecules, while the inactive (reference) bead balances the reaction and compensates for normal changes in the ambient environment. The sophisticated design and construction of Det-Tronics catalytic sensors provides excellent sensitivity, response time, and resistance to physical shock and vibration.