Communication cables should come through the top. The top of this cabinet allows terminated cables to drop in through the sliding top cover. Before starting to populate, be sure to check the service loop length is long enough.
Once closed, the compressible memory foam sheets, with a fire and chemical retardant impregnated throughout the material, seals off the top to eliminate airflow leaks. Max opening is 15.25″ wide x 19.50″ deep.