Black Cone Seat Spline Closed End 6-Lug Wheel Installation Kit (W56015SB) by West Coast®. Thread Size: M12 x 1.5. Overall Length: 1.38". Material: Steel. Quantity: 24 Pieces. A complete installation kit for your wheels can save you lots of time and money by getting all the things you need to put your wheels on together in one handy package.