That is UP TO 25J. Please understand, Propper AMMO and ambient TEMPERATURES required to get the full potential from these markers. You probably won't make 25j with 1g ammo, nor 3g. You'll need something heavier. You need to dial in what works best for what you want.
More muzzle energy, higher weight To an extent. Ideally, 80F ambient temps and 6-8g shaped/fsr ammo with fresh co2 works best for muzzle energy with this setup. 5 CO2 cartridges, 3 magazines, 25 shot cups(unfilled), 25 rubber round balls and 1 CO2 puncture button cover.