The 12-503 is a Plug to Plug-ended booster cable.  This 2-gauge duplex cable is 12-feet long with non-reversible plugs on each end to ensure proper polarity when plugging into the mating connector.  Plugs join with other 500 Series plugs.  This cable is appropriate for heavy duty boosting up through semi tractors.

Warning: This product may expose you to chemicals including lead which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov