Active Storage mRAID16 Quick Start Manual page 5

(5) Fasten screws.
(7) Check the installation of the ball bearing guide rails.
(6) Install a ball bearing guide rail bracket.
Check the distance between the left and right guide rails, and
ensure that the two templates can snatch into the ball bearing
guide rails.
Check that the ball of the ball bearing guide rail has been
placed at the most front end of the middle rail.
Check that the edges of the middle rail and external rail are
on the same vertical plane.