Premium ground bolt kit for car audio systems. Simply drill a 1/4" hole, and use a 1/2" socket on an impact driver to install this secure and reliable ground onto nearly any location on your vehicle. This kit includes: (Quantity of 6): 5/16-18 x 3/4" self threading zinc plated hardened steel ground bolts (Quantity of 6): 400 series stainless steel external tooth lock washers for superior corrosion resistance and holding power (Quantity of 6): 2" sections of black heat shrink suitable for wires with a diameter of less than .625" (5/8"). 3:1 shrink marine grade. 3/4" size before shrinking. min size 1/4" after shrinking. If you'd like the heat shrink not cut please add to notes. Thank you for looking.