Though they look very different, UOP SimulFlow (TM), Koch-Glitsch Ultra-Frac (TM), Jaeger CoFlo (TM) and Shell ConSep (TM) trays fall into the same category of trays using inertial separation technology. However, flooding mechanisms and the trends of entrainment and efficiency are different due to their different working principles. This paper provides a detailed analysis of these trays using available information from literature and U.S. Patents. Efforts are also made to interpret the observations reported. In terms of tray efficiency, it is found that SimulFlow, Ultra-Frac and CoFlo trays are typical point efficiency devices due to a completely mixed liquid pool on the tray deck, while ConSep trays can take advantage of liquid concentration gradient on the tray deck, which makes this tray attractive among all ultra high capacity trays.