1 There is no negative ion machine, the thumb is in contact with the metal sheet on the front
Detail
2Do not touch the metal sheet on the back with your fingers
Detail
3Keep a certain distance from the negative ion machine
Notice
This model is only suitable for testing the approximate values of negative ion air purifiers and negative ion generators. The value fluctuates greatly (because there is no peak lock function). If you mind, please take it carefully. You can consider other more precise testers with peak lock., Except for this problem, once sold, there is no return or exchange.