The first u32 describes the vibration device type which is a Linear Resonant Actuator used in Nintendo Switch controller hardware. The second u32 describes the vibration device position, in this case distinguishing between left and right vibration actuators. Pro Controllers have 2 LRAs each that can vibrate independently of each other, which means they have 2 distinct vibration device handles to distinguish between the two actuators. Similarly for joycons, the left joycon can be distinguished from the right joycon through the vibration device handle since each joycon has 1 LRA.