Ridgeyard 18L / 4.75GPM LPG Propane Gas Tankless Instant Hot Water Heater With Shower Head Indoor Bathroom Supplies ISO approved and CE certificated; 85% thermal efficiency.Rated Heat Input Power (KW):32 Stainless Steel Panel,LCD screen LPG ,Automatic electrical pulse ignition with no standing pilot, operated by 2 D Batteries Winter/summer knob: used to switch from winter mode to summer mode or in an anti-clockwise direction Water knob: used to switch between maximum water flow and minimum water flow. Gas knob: used to switch between maximum gas in amount and minimum gas in amount