I have two theories on what the device strapped to keamy's arm is;
The first, is its a heart rate monitor that will trigger the bomb if he dies
The second is that the device is something to do with the jewish religion. I just watched an episode of NOFX backstage Passport, ep 6 it was, and when NOFX visit the Wailing Wall, or Western Wall in Jerusalem one of the band members says a prayer at the wall for his recently deceased parents, which is tradition. Whilst he is getting ready for a prayer, a Jewish dude straps a small black box to the guys arm with black tape looking stuff, i tried to find out what it is but couldnt find anything, anyone Jewish?