Sealand / Dometic Toilet Bowl Cleaner removes tough stains and grime from toilets in two minutes.

Sealand / Dometic Toilet Bowl Cleaner is formulated to disolve mineral deposits that build up between the flush ball and the seal.

Also, an excellent cleaner for counter tops and sinks.  This is a very popular item with Boaters and RV'ers.

Does not damage rubber componets as many off the shelf cleaners will do.