Thermal Color Changing Changing Version Red to Yellow Royal Blue to Purple Green to Lemon yellow. Fits with most 510 Cartridges (maximum – 11.5mm) USB-C Cable Included 510 Battery fits up to 2grams Carts Voltages: Green – 3.0V Red – 3.8V Rainbow – Preheat Instruction: press button 5 times to power on/off device. press button 3 times to adjust voltage. press button 2 times to preheat.