Ray (RaysReef) uses them. The type he uses fits perfectly in the upper lip of the pee cups from hospitals (Which he sells as well LOL). It is very secure for shipping/transport.
I'm not sure where he gets them, but he should be able to hook you up if you PM him.
I was looking at their page earl;ier and couldn't find anything. I was thinking that you would have to e-mail them. The ones that Ian sells is def what im looking for.