Stroke length of 4.0mm, 2400mAh battery for long-lasting use. Authentic product - Brand: AMBITION - Model: Machine - Stroke Length: 4.0mm - Weight: 201g - Size: 132×32.5mm / 146×32.5mm - Voltage Range: 4.0-12V - Battery Capacity: 2400mAh / 1800mAh - Usage Time: 8-10 hours / 6-7 hours - Speed: 12V 13000 Rpm - Noise Level: 52-55dB I'm not sure what else to write. I've only used it twice for testing. I have many other drawing tools, so I want to sell this one. It can be used by beginners and experienced professionals alike. I will also include a brand new, genuine pen tip and other accessories in the box. Please feel free to ask any questions. Thank you for looking.