That's the PIR fresnel lens. I'm not surprised they didn't know that. I've built more trail cams than I can remember. I also own a half dozen Browning trail cams and the, 0.9 Focal length Wide Angle Fresnel Lens, from Snapshot Sniper for $3.00 looks like it could be trimmed to fit and work. I haven't ordered parts for years and the homebrew market has kinda died out but it's worth looking into.When I described it to Browning Trail Cam repair center, they called it the PIR. It is the tinted curved piece on the outside of the camera.