The maximum head circumference is 60 cm, The helmet supports touch, voice and remote control. The product does not contain batteries You need to bring your own battery The electrical box is hidden in the back of the black pad on the back. Remove the back cover before use Package includes: 1 * helmet 1 * remote control Battery Power Remote Control Requires battery: 2 * AAA battery (Battery not included). Helmet Requires Battery: 4 * AA batteries (Battery not included)