C4K-SLOT-CVR-E The blank line card (C4K-SLOT-CVR-E) must be installed when either of the following two situations occur: If your Catalyst 4507R or Catalyst 4510R switch chassis has a Supervisor Engine 6-E (WS-X45-SUP6-E) or a Supervisor Engine 6L-E (WS-X45-SUP6L-E) installed in slot 1 and slot 2 is empty, you must install the blank line card (C4K-SLOT-CVR-E) in slot 2 rather than a blank faceplate (C4K-SLOT-CVR) . A blank faceplate covering the slot 2 opening does not direct sufficient airflow to adequately cool the Supervisor Engine 6-E or the Supervisor Engine 6L-E. If your Catalyst 4507R or Catalyst 4510R switch chassis has a Supervisor Engine 6-E (WS-X45-SUP6-E) or a Supervisor Engine 6L-E (WS-X45-SUP6L-E) installed in slot 2 and slot 1 is empty, you must install the blank line card (C4K-SLOT-CVR-E) in slot 1 rather than a blank faceplate (C4K-SLOT-CVR) . A blank faceplate covering the slot 1 opening does not direct sufficient airflow to adequately cool the Supervisor Engine 6-E or the Supervisor Engine 6L-E.