iOptron 3305A SkyTracker Ball Head (Black) Designed for users to mount and remove camera and lens quickly. Large aluminum alloy ball (1.5 inches, 39mm in diameter) provides super smooth movement and super strong grip. 360 degree panning. Head Tilt: +/- 90 degrees The safety stops on the quick release plate prohibit your camera from accidentally slipping out of the quick release adapter (easy to remove with hex wrench if desired). Also features 3-screw-position top plate. Screw size: 1/4 inch for camera; 3/8 inch for tripods. Also includes 1/4"-20 / 3/8"-16 tripod adaptor piece. Weight: 0.875 lb. Working Height: 3.875 inch. 2 Spirit levels. Load Capacity: 20 lbs.