On top of that the technology proliferation and availability of decent commercial products basically means old/damaged units can get replaced, both NV and thermal.You’re probably right. depending on the manufacturer these numbers could be completely different. I was looking at the higher end American made NVGs, likely the kind left for the ANA, but considering the videos show Gen 2 tubes breaking down at 400/800 hours, it’s likely the lives of the tubes are 1000 hours max.