Martin Korenek explaining how exclusion devices work when attached to the wall aboard Marine Corps Base Camp Lejeune Aug. 7. The exclusion devices cause bats roosting in walls the ability to leave the insides of structures but prevent the bats from re-entering. - Martin Korenek explaining how exclusion devices work when attached to the wall aboard Marine Corps Base Camp Lejeune Aug. 7. The exclusion devices cause bats roosting in walls the ability to leave the insides of structures but prevent the bats from re-entering.