High capacity of battery: Capacity of 1500 mAh enables artists to work for a long duration of 4-6 hours. When the battery has run down, the RCA connector can be replaced.Simple operating system: LED screen shows battery, timing, and voltage more clearly. Artists can easily adjust the voltage by pressing buttons.Instant start-up function: Start-up function will be automatically activated at power on. Even large rows of needles can be used easily.Variable stroke: 2.4/ 2.7/ 3.0/ 3.3/ 3.6/ 3.9/ 4.2 MM¨CFor all artists from Tattoo to SMP.