Cisco SRS Series Installation Manual page 198

Steps
b) Insert the cable trough hooks into guide slots, and let them slide down and lock into place.
c) Insert the 12 M4x14-mm flat head screws (six on each side) and use the screwdriver to turn the screws clockwise
to attach the cable troughs firmly to the chassis.
d) Pull the Velcro cable straps taut to hook the troughs to the chassis.
Figure 96: Front Vertical Cable Troughs Installed Fixed Configuration Power Shown-
This option only works with trough kits 69-1199-03 and later.
Note
Cisco CRS Routers 16-Slot Line Card Chassis Installation Guide
178
Installing and Removing Exterior Cosmetic Components