For dragons like beardy's etc. They don't have many heat receptors on their underside so heating from below they do not feel, If i the heat rock did over heat they would not feel it in time and get burnt. Something like a blue tongue skink or leopard gecko will feel the heat rock if it were to over heat and hop off, Exo-Terra has a thermo stat and is water resistant other heat rocks like reptile one i have noticed say nothing about a thermo stat and nothing about being water resistant or water proof if say a wet water dragon decided to sit on one of these it could get electrocuted. Hope this helps