Does not fit protac 2l - Streamlight ProTac Remote Switch W/Tailcap

Item is incorrectly described. Package just arrived, and it will not attach to my brand new Protac 2L. The threads are considerably differently pitch, this remote switch being a considerably coarser thread than the factory tail cap. I double checked the item numbers to make sure I didn't get the wrong item by chance. The item itself is of fine quality and function, I just wish I knew which model it was actually meant to attach to. Real bummer as I was hoping to have a working small weapon light.