What is a really good Marble sealer for the bathroom?

I've recently installed a Marble shower and (http://maplered.com) bathroom floor.  The shower is completely done in Marble (http://www.lightemprador.com) , floor ceiling, inside and (http://maplered.com) outside walls, some tumbled. What is a really good sealer. Easy to use and (http://maplered.com) hold the integrity of all the Stone (http://g603.net) .