RECHARGABLE PORTABLE COFFEE GRINDER: The battery is built-in lithium, and it is charged via USB, taking approximately 2-3 hours to charge fully. In continuous grinding, it is possible to grind for approximately three to four hours. It is capable of grinding up to 20-25 grams of coffee beans per time, making two or four cups at the same time. In comparison with a manual coffee grinder, it is more time and effort efficient. SIMPLE OPERATION: The coffee will be ready for you in no time with just one touch of the button. It is important to note that once there are no beans in the coffee grinder, it will stop grinding for safety reasons. COARSENESS ADJUSTMENT: The coffee grinder features a multi-grind setting that lets you adjust the coarseness of your ground coffee for the desired brewing method, from espresso to French press. The portable electric coffee grinder guarantees even coffee grounds regardless of grind coarseness. NO MESS OR FUSS: Its small, portable design and wireless operation make it convenient to use at anytime, anywhere. There is no mess and no fuss when using the transparent powder bin, since it is securely closed and will not leak. To clean, simply use the provided cleaning brush to remove any unwanted coffee powder.