This sale is for a really excellent condition Mamiya Tripod Adapter Collar 3/8″ to 1/4″. Ideal replacement if you have lost yours or a previous owner has removed it!
This adapter converts the built-in 3/8″ tripod socket in the base of your Mamiya camera to the more commonly used 1/4″ fitting and includes the special locking screw that stops the adapter from coming back out by accident.
Try finding another one – very hard to find.