4-1/2" Glass Ball as shown will fit 5/8" Rod or smaller. - NOTE": Some of the old hollow 5/8" tube rods had a removable tip (shell top). The ball will not fit over the shell top but the top is easily removed by firmly grasping the rod and twisting the top while pulling upwards. Sometimes the top is fused on from age and it may be difficult to remove, but IT SHOULD COME OFF.FREE U.S.A. First Class Mail. - Thanks for Looking.