I've never heard of an "improved skeet" choke either, but the name does make some sense. The name implies a constriction that falls between Skeet and IC. Seminole makes a choke like that, with a constriction of .008 compared with Skt at .005 and IC at .010 (in 12 gauge, that is - constrictions would be less in small gauges). I think it is unfortunate that Seminole has chosen to call theirs "Skeet II", which is a name used in the past for a choke that falls between IC and Mod - the same thing that is now called LtMod. It would make more sense for Seminole to call it "Improved Skeet" rather than "Skeet II". Perhaps some other maker does use the IS designation for what Seminole calls SktII, I'm just not familiar with it.