Turn your favorite rotary machine into a wireless powerhouse with the Critical Universal Battery. Available in both RCA and 3.5mm (Cheyenne) connection types, this battery pack is compatible with most rotary machines. The Critical Universal Battery offers an ergonomic, balanced, and intuitive interface that provides an experience of true freedom. We sell all products individually, we also sell them in bundles if needed as well. Keep your workstation organized while charging your Critical Universal Batteries with the Critical Universal Battery Dock. Compatible for both RCA and 3.5mm connection type batteries. This dock features a no fuss easy battery swap, so you can swap out batteries quickly with just one hand. Built in magnetic bottom allows unlimited mounting capabilities for easy access during your tattooing sessions. Features: Universal Battery Pack Features: Compatibility: most Rotary machines, Pens, & Cheyenne products. Available in: RCA & 3.5mm (Cheyenne) connections Run Time: Up to 10+ hours of tattoo time (depending on voltage use and machine) Voltage: 4v-13v with Critical Core (consistent and stable voltage output) Includes: USB-C Charging Cable Dimension: 2.47" (L) x 1.26" (W) & 2.0 oz Optional Dock Charger: Easily charge up to 2 of your Critical Universal Battery. Batteries fit easily, precisely & will stay in place at most angles Quick battery swap; "one handed battery change" Approximately 2-3 hrs charge time from depleted to full Includes: USB-C Charging Cable & Wall Plug Dimension: 2.0" x 4.0" x 1.20" 2 - Battery + Charing Dock: We also sell the 2 battery + charging dock for $539.99.