It's a 2 part Rock... The Adapter to the Truck then either of the sizes.... Get one base and BOTH outer Rock adaptors... I use 1/4 inch 99% of the time but have the 1/2 inch if needed.... Get Ron's Wrenches and Square Drive bits too... I snapped 3 on a QC Change Out that I gave up on that had forever red lock tite... It is important to properly heat the inside of the QC.... A Soldering Iron inserted UP into the QC works best in "MY" opinion....