" A flashlight is...like a candle.   A very, very small version of the light in my weapon.  And it isn't magic, it's math.  Add what you earn.  Subtract what you spend.  And when you get to a trading center, they can process the addition and subtraction, the cred stick just keeps track of it.  Kind of like a fancy I. O. U.  It uses fingerprints and, if needed, DNA...Um, like, it tastes your spit, so if some one steals it, it wont work.  And thanks for the trading advice Shyael, I was thinking more if I need food or a weapon than a total exchange, but I'll minimize purchases until I can get to a trade center."