If you want to put a new ballhead on your tripod and it doesn't fit, here's the screw you NEED! 

5 in1 Tripod Head Monopod Flash Light Stand Adapter Screw 1/4-3/8 Male to Female Photographic Studio Accessories

Material: Aluminum
Type: Use for Professional Tripod / Monopod / lightstand
Use: Point & Shoot Cameras
Model Number: 1/4 inch to 3/8 inch

Folded Length (mm): 2.8
Max Extened Length (mm): 3
Weight (g): 50

Please allow 2 - 4 weeks Delivery time!