... Four digital Nixietube4. Control Range: 5%-95%5. Precision : ±0.1%6. 4 Pre-set : 5%, 16.25%, 72.5%, 95%BUTTON INSTRUCTION1. Select Button ... : When the corresponding indicator light turns off, press ↑ ↓button to adjust PWM value 5 ... press ↑ ↓button to choose 4 kinds of pre-set : 5%, 16.25%, 72.5%, 95%2. RED4 POWER: The Oil adjusting speed device ...