Tank Tattoo Pen Machine: Dragonhawk Tank 4.2mm stroke length quiet operation, adjustable needle protrusion, and a broad frequency bandwidth for any tattooing style. Active Frequency Reduction: the Tank tattoo pen has original mechanical design to reduce motor frequency then get more powerful hit, this mechanical come with custom motor Ideal for powerful lining and color-packing. Game-changing Machine: Dragonhawk Tank tattoo pen machine is the world's first active frequency reduction tattoo machine, the frequency and hit of this machine intuitively adjusts to whatever surface you¡¯re tattooing. Specifications: Weight :135g Diameter:28mm Length:108mm Stroke:4.2mm Working Voltage:5-12V Speed:12V/ 10000RPM