Description: Brand new and high quality Features: Ball head diameter: 18mm, suitable for tablet/mobile phone holders that can connect to 17mm/18mm ball heads. Base screw hole size: standard 1/4 or 6mm screw mount. Installation position: can be installed above the screw of the tripod/selfie stick/camera holder head. Applications: connect the mobile phone/tablet to the tripod mount, allowing the direction to be adjusted 360 degrees. Easy to Use: Attach the adapter to any mount that fits a 17mm ball head, then use the 1/4"-20 mounting bolts to secure your camera. Specification: Material: Nylon Length: Approx. 40mm/1.57in Ball Diameter: Approx. 18mm/0.71in Base Diameter: Approx. 21mm/0.83in Base Screw Mount: Standard 1/4" Notes: Ball head adapter only; other demonstration accessories are not included. Please allow 0-1cm error due to manual measurement. Make sure you don't mind before ordering. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you! Package Includes: 1 pc Ball Head Adapter