Welcome to our store! Ball head diameter: 17mm (suitable for tablet/mobile phone clips that can be connected to a 17mm mounting ball head) Base screw hole size: 1/4 or 6mm Installation mode: above the screw head of a tripod/selfie stick/camera tripod Purpose: Link your phone/tablet to the tripod mount, allowing the direction to be adjusted 360 degrees Due to manual measurement, please allow 0-1cm error. Make sure you don't mind before ordering. Due to differences between different monitors, the pictures may not reflect the actual color of the item. Thank you Quantity: 1 piece (ball head adapter only, other demo accessories are not included) Product color: black Product size: Ball head diameter: 17mm Your satisfaction is our top priority. We will provide you with the best service. If you find any problems after receiving the product, such as damage, incorrect quantity, etc., please contact us immediately and we will provide you with the best solution!