The Jobu Design 3/8" to 1/4" Adapter Bushing is used in ballheads or cameras or any supports that have a built in 3/8" thread where you want to use a 1/4" support.
Reviewed by 2 customers
When ordering a ball head for a tripod or monopod make sure that you check to see what size the base diameter is. I did not and when I got my head and was excited to begin using it I was so disappointed because the bolt part on the tripod and mono pod was to small to fit into the base of the ball head. Upon calling customer service is when I was helped and the adapter bushing was recommended. My suggestion would be that you put it as a recommended purchase or included it with the order.
I need to add a ball head to an old tripod and the size of the threaded hole and stud were different and this allowed me to attach the head. It works vine.