The #1509 is an extra complete wiring kit for the Black Box. Please Note: if your Black Box is more than 5 years old, you may need an earlier model plug - contact Pro-Troll at mail@protroll.com to determine which plug you need. Kit contains all of the parts needed for a Black Box installation except the Black Box itself and the Black Box mounting bracket.  It allows the Black Box to be installed on a second boat.    
Items in the Kit include a spare Black Box plug, all wires with end fittings for connecting between the plug and two downriggers and two spiral contact sleeves