... fiberLeft key function:“Power” key: press in this key, Electricity get through, press out this key electricity power off.“Hold” key: ... press in this key, data keep showing, press out this key preparing test.“UV365”key: use UV365 ... humidity under80%, temperature 20±10°CInsurance:12 Month ( 1year ); within this period any problem not man damage. We replace or repair andcalibration ...