MSA 815444 Advantage 200 LS Series Half-Mask Respirator, Medium Multicolor The listing states a relay

The listing states a relay output that drives exhaust ventilation (or an alarm) automatically when H2 rises

and a water-resistant shell for variable conditions

and Class I Zone 0 IIC T4 / Zone 20 IIIC T135C

so match it to measured exposure

MSA 815444 Advantage 200 LS Series Half-Mask Respirator, Medium Multicolor The listing states a relayAMAZON CUSTOMER RATING: 4. 6 5 WC Safety research note on the MSA Half Mask Respirator, a half mask respirator. Rating shown is the Amazon customer rating at the time of writing, not our own score. Specification based assessment by Steven Eaton, WC Safety Editorial, from the published MSA listing and NIOSH 42 CFR 84 and OSHA 1910. 134. We have not hands on or laboratory tested this product. The MSA MSA 815444 Advantage 200 LS Series Half Mask