... (Under Qmax)Service Life≥10 Years ModelFQ-SL---steel shell, LCD display, left entrance, G1.6/2.5/4.0FQ-SR ... ---steel shell, LCD display, right entrance, G1.6/2.5/4.0FQ- ... SB---steel shell, LCD display, left/right entrance, gas leaking alarming port, G1.6 ... feel free to contact us for any questions. Direct-reading Remote-transmitting Diaphragm Gas Meters