Main nero injectors are at checkpoints and research sites with red blinking beacons, cant miss em once you spot the buildings. Checkpoints show up on your map right away but research spots need some exploring, sometimes hiding in caves after clearing ambush camps. Each one boosts health stamina or focus by 25 and theres 30 total to collect which maxes everything to 350, pretty sweet for fighting hordes. Little bear lake is your first shot at one during story stuff, good idea to grab it then.

Watch for those research sites with blinking lights when exploring caves, might be interesting to check near where youve seen nero researchers hanging around. Maxing these out makes a huge difference in fights, specially when you need that extra stamina for running or focus time for headshots later on.