By diverting the urine away from your composting toilet, you reduce the smell to almost zero meaning that you can have your toilet closer to your living space. It also gives the option to collect the urine in a tank to be used as fertiliser. 
 
This version attaches to the underside of the toilet seat or box by use of a bracket that allows the diverter to be removed and cleaned.  Connects to a standard 19mm ID alkathene pipe.