DCS 20 Inch Built-in Outdoor Storage Drawer: Single Drawer Installation Instructions - Manual (Page 11)

11 11a REPLACE ALL DRAWERS
To replace the drawer(s)
1 Extend both guide rails out.
2 Engage the drawer rails into the guide
rails. Pull the guide rails forward until
they ‘click’ into place.
3 Push the drawer all the way in (there
will be some resistance) to completely
engage the drawer.
Extend guide rails Engage drawer rails