... meter 1.LCD display 2.Data-hold switch 3,high quality Digital llluminance meter Features 1 ... 20,000 lux ranges ,respectively .3.Power Switch :The power switch key turns the illuminance meter ON or ... OFF.4,Data-Hold Switch :Pressing the HOLD key selects HOLD mode , ... the illuminance meter to resume taking measurement s,5.Range Switch :Pressing the range key changes 20 lux,200 ...