Sometimes the first question is the easiest. We have bundled our Complete 15 mm RCE Kits in several ways to suit your specific needs. The first question to ask is whether or not you have an MSR Rotator. If you have one already and you wish to add a Complete 15 mm RCE Kit, select the "Without MSR Rotator" option. If, like most users, you require a dedicated MSR rotator to go with your Complete 15 mm RCE Kit, select the "Includes MSR Rotator" option.