Eric of Gun Gamers says that the EMG CGS SCI-SIX Tracer Unit is a solid one for airsoft use... "Today, we take a look at a product that isn't complicated, but it accomplishes what it sets out to do very well.  Thanks to Evike for sending the EMG CGS Licensed SCI-SIX for review.  If this solves a problem you've had, or you just want a solid tracer system you can buy one at the link below and we'll get a little cut of the action for sending you that way."