D30 guide crossing runner and D30 successor cover can not be installed at the same time. By attaching the D30 joint cover, the thickness of the rail increases, it interferes with the plastic roller part of the D30 guide crossing runner, making it impossible to move the runner.
By using the continuous cover, it is possible to link (fix) the two rails and the rail and it will be a smooth liner movement. It is slightly different if there is not. Those who use two rails, please come.