Just went down to Ruby Photo,Bowens agent to enquire about Wireless Triggers and was
recommended their Impact model.Am still using their Bowens 400Ds but have not decided
yet.Perhaps you could check it out from them.Cost 100.00 per set- trigger/transmitter.
even in closed environment and inside a room, radio frequency can still pass through normal concrete. so unless you're in a customised steel-reinforced room, illegal use of radio transmitting equipment can still be tracked.