I have this in a setup that's putting out about 430 FPS, and I'm pretty happy with it. I'm not sure of the FPS range that these are meant for, but it's working fine and is not getting worn down at all after about 2,000 rounds.
I have heard that this is basically the same design as Firefly's bucking, but I've never seen a Firefly bucking, so I don't know 100%.
-This improved my groupings a good bit over just a standard Prometheus bucking, instead of getting a BB that flies randomly off-center every 20 rounds, I'd guess that this number is down to about 1 in 50, maybe better depending on what weight/brand BB's you use.
-Holds up well to 430 FPS.
-I am able to get reliable 1 to 2 shot hits on someone who is only exposing their upper torso above from 120 ft.
-There are definately more expensive buckings than this 2G bucking, and I think $14.00 is a good price.
Rating: [5 of 5 Stars!]