How powerful are theses?

http://www.sparkfun.com/products/10534 http://www.sparkfun.com/products/10532

It says 500 feet so im thinking not to shabby. However (this is a weird question) do you think the signal could go through a ceramic lid of a toilet? (Not sure if the lid is actually ceramic but that type of material ie not metal/plastic) Lid as in the top/lid of the back of the toilet where the water and valves are. I would say its like .5-1in thick.

Awesome just what i was looking for thank you!