This is PN 901.107.729.00-AFT, so it is an aftermarket part. The original is apparently not available. This is part No. 22, on illustration 104-10, and is the "filter" that fits inside the right air cleaner and connecting hose that runs from the oil can to the right air cleaner. It fit perfectly, and will probably keep oil out of the air cleaner. It performs the function of a strainer for the oil breather system. Even thought it is an aftermarket product, I think it will work well. Only the right air filter will tell; we'll see how black it gets.