... Data display: Light Four digital Nixietube4. Control Range: 5%-95%5. Precision : ±0.1%6. 4 Pre-set : 5%, 16.25 ... indicator light turn on, press ↑ ↓button to choose 4 kinds of pre-set : 5%, 16.25%, 72.5%, 95%2 ... . Before left factory, all the data have pre-set well, don't change it by any way, ... lamp light, and press arrow ↑ ↓ to choose pre-set rank, and press select button again, indicator lamp power-off ...