This kit is a must for installing and removing the barrel on the G36/ SL8 platform. The barrel mandrel goes through the receiver to secure the trunion for barrel installation and is a must for securing the barrel to install muzzle devices as well. Torque the barrel nut to 45 ft lbs. For muzzle device installation refer to the recommended torque spec from the manufacturer of the Muzzle device, most are 35 Ft lbs for reference. Some SL8 barrel nuts have thread locker from the factory and require heat to release the thread locker, If you run in to one with thread locker its best to use an inductive coil device to carefully apply some heat to help loosen the thread locker, with out that you can still damage the receiver.