Its an Amp shield and usually Amp shields boost the first shot of your gun by a large number. This only works if the shield is at max, so for snipers its amazing. But after that first shot it takes up a portion of the shield and lowers it like you got shot. Like I had one that had 6000+ shielding, and like a 4000+ amp boost, but took away 1500 shield when I fired an Amp shot.
The Bee, has no shield cost. So EVERY shot is amplified. The only thing about the shield is it usually has a low shield rating compared to others of its level. But it has an INSANE amp boost.
So against Bosses who usually have a few seconds between their attacks, you can usually refill your shields and fire like 6k+ boosted shots at them until they hit you.
In fights against multiple guys however, its more of a liability due to its low shield rating.
But for the most part, things cheap as hell.