As long as there are not colourful and act as a distress signal, i cant see why they cant be used at any liberation site, they are no harm, but i think, JMO that when you set them off, Percy just moves awe a couple of miles from the liberation site until the birds are free. A no a guy tryed this when liberating the doos from a toss and they got well melted, make sure they are well awe from the transporter at the time of liberation.