The cam-jam Quattro post clamp is 2”. The half shells change that to the size of the 2nd lowest post of the MKV four stage post. And the ring goes to the lowest post section which is smaller and gives it the same diameter as the 2nd lowest post. So the post clamp with the half shells installed will fit. It has elevated edges, so it follows the cam-jam Quattro automatically when you move it up or down the post.