When installing the Tolerance STACK seat mounting solutions, a heater harness extension is needed in order to prevent the harness from getting snagged on anything when the seat is being moved/adjusted. This is only necessary if you do NOT have factory installed heated seats with factory installed, dash mounted heated seat switches. 
 
NOTE: This extension harness is INCLUDED with your seat installation kit if you do NOT have factry heating but is available separately just in case a replacement is needed.