Just got a ZCO but haven't mounted yet. Went shooting yesterday and brought it along just to take a gander. Very hazy in the morning - Athlon Ares BTR looked like it was fogged up, DMR2 similar but less so, Trijicon Tenmile tough to cut through the haze, but could tell it was haze, and Burris XTR3 cut through best, but still very compromised at distance. ZCO had nothing at 1 mile, and nothing at 500 yards, just a bit more white around 1K yards. The difference between the Chinese Athlon and the XTR3 was approx the difference between the XTR3 and the ZCO. Confirmed on good days, mirage days, rain days, and now haze, that ratio holds.