Mercoid-brand gas pressure/differential pressure switches distributed by Dwyer Instruments Inc. feature ranges of 1-30" or 0.5-5 psid. Available with a SPDT mercury switches or SPDT snap switch, the gas pressure switches also feature maximum deadband of 1.9" Wc, 0.4 psid, 1.3" Wc, 0.3 psid, 4" Wc, or .5 psid.