Arena 149's limit is 350 FPS tested on 0.20 gram BB'sHPA powered Airsoft Gun's power is measured by joules and have a limit of  0.95 Joules which is 320 fps on a 0.2g and 287 FPS on a 0.25g.The Heaviest BB weight that can be used at the Arena is 0.25 grams.Bio or Biodegradable BB's are NOT PERMITTED