Rutrag
Aquarium Advice Addict
Tanga has these for $14 if you need one for your RO/DI unit.
http://tanga.us1.list-manage.com/track/click?u=59aafc6d9861ad792de1d32fb&id=a358870c74&e=bed98198b4
http://tanga.us1.list-manage.com/track/click?u=59aafc6d9861ad792de1d32fb&id=a358870c74&e=bed98198b4