... ) fast calibration device Product Name: Sales! Portable M40 gas detector (CO,H2S,O2,LEL) M40 SPECIFICATIONS: Size: 4.30" x 2 ... with Backlight SENSOR SPECIFICATIONS: Gas Range Resolution T90 Carbon Monoxide (CO) 0-999 ppm 1 ppm 48 secHydrogen Sulfide (H2S) 0 ... free to contact me. Thanks. Sales! Portable M40 gas detector (CO,H2S,O2,LEL)