Potentiometer: large clockwise, small counterclockwise. Nixie tube: display output voltage Nixie tube switch: it can be turned off when not in use. Fan: The heat sink temperature is 50C, and the fan starts. Stop working at 40 C. Input: 25-90V (cannot exceed 90V) Output: 2.5-60V (voltage regulation first meets the conditions compatible voltage reduction and cannot be boosted) Power: 1500W (MAX) Current: 50A (MAX) Please note: There is a slight color difference or discrepancy in kind, please don't mind, thank you! Material: Metal colour: As shown Package Contents: 1 x 1500W 50A module Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.