This Plenum rated 1000 ft CAT5 bulk cable is great for IP network applications. Get a perfect fit without a tangled mess of extra cable. Plenum rated CAT5 cable has a jacket that meets specific ANSI requirements to be flame retardant and have low smoke production. The idea being that if the building is involved in a fire, the Cat5 Plenum cable will not burn as easy as a standard PVC jacket, and will produce less smoke than a typical Cat5 cable if it does catch fire.
Deciding if you need plenum typically will come down to specific requirements of the code dictating certain aspects of the job. For example, if you were making an office that was HIPPA compliant, Plenum rated cable would most likely be required to meet the code specifications for that building.