There has been much in the news lately about counterfeit goods sold over the Internet, mostly through third party dealers. At first glance, these profiteers (I really can't use the term marketers) claim either they're supplying the exact item specified, or an item that matches its specifications.
L-com Inc. recently checked on one of these suppliers, and what they found very definitely leaves you in a "Buyer beware!" mode. They detail their findings in a posting to their web site that includes a link to a 14-page report from an independent testing lab detailing the exact characteristics and problems with a wire listed as "equivalent."
In a nutshell, the 24 AWG copper Category 5e Ethernet cable turned out to be 26 AWG copper-clad aluminum that came no where near meeting the requirements for Category 5e service. And the problem isn't limited to cables. Connectors were also found to be made using inferior materials or manufacturing techniques. One connecter tested used flashed gold for the contacts, which easily rubs off exposing the base metal to corrosion. The cable using that connector had an insertion loss of -12 dB. (For those not familiar with dB measurement, signal strength drops by half for every -3 dB. So a -12 dB loss means only one-sixteenth of the signal power was getting through.)
Other problems were found in cables rated for plenum or riser applications had little to no fire retarding capacity. The insulation on these cables burned readily with dense smoke, which would make egress from a burning building difficult due to poor visibility and toxic fumes. These cables also act like lit fuses, transmitting the fire from one part of the building to another -- even floor to floor.
The key to not being a victim of these fake products is, of course, to know what it is you're buying. As David Gallagher, L-com Product Manager states, "When buyers know and understand the consequences for buying just the cheapest cable without checking the actual construction, they are spared the enormous expenses and damages that could occur."