We currently do not carry a box where the rats can enter to die. Like other rodent stations, the Protecta EVO Circuit Stations offer access to rodenticides for the rats to consume and they can exit freely. Yes, the rats dying under the house or in the wall voids would cause an odor. We recommend that you select other types of traps for rat control including glue boards. Please follow the link below for helpful tips and product recommendation for trapping rats.
Rat Traps-http://www.domyownpestcontrol.com/rat-traps-c-21_127.html
http://www.domyownpestcontrol.com/how-to-get-rid-of-norway-rats-a-258.html
The Protecta EVO Circuit Bait Station does not contain a concrete block with the station. We do offer these types of bait stations on our website and they can be found here.