It is so you can flash the side of your gun at someone else in a dark/smoky/obscured room and they can see the signal, but you don't need to completely surrende

It is so you can flash the side of your gun at someone else in a dark/smoky/obscured room and they can see the signal, but you don't need to completely surrender situational initiative. The tape is reflective to help in this case. The person flashing the sign knows it is not 100% certain to work, but it better than metallic crickets or pass phrases.