Ours didn't always work and we never knew when they did or didn't. One took his chances on hunkering down behind the tank and if he didn't know you're there, anything could happen. I almost was backed over by armor before even turning eighteen because a driver didn't know...not his fault really. Just missed me. Ours were on the Centurions, we didn't have any Shermans left by the time I was around there.