4 17mm ball head bracket adapters with 1/4 screws, compatible for phone holder, bracket, tablet holder This 17mm ball head bracket is designed to connection any 17mm double ball head arm and bracket. To ensuring compatibility, it is recommended to check if there are 1/4 inch screw holes at the bottom of the camera The 17mm ball head bracket is compatible for sports cameras and driving recorder with 1/4 interfaces This 1/4 inch to 17mm ball head adapter is compatible for global positioning device stand and other brands' 17mm double ball head arms Due to its 360 degree rotation, you can use it to build a phone camera stand or use it in conjunction with a sports camera inside the car