Lately I've been trying to work on the different kind of half guards, especially deep half guard (see Aesopian’s Totally Awesome Journal if you don't know what I mean). But one of the major problems I have is the knee slide pass. The traditional way to do it is to get an underhook, but it can be very effective even without this. From any half guard positions, people will do the pass and let you come to your knees so that they can attack with a brabo or anaconda choke. Basically it takes you out of your half guard game, and forces you to play a defensive turtle game, or a wrestling game. Now I can see two solutions to this. Either A) not let them twist their knee out in the first place or B) take advantage of the fact that they don't have an underhook to grab a single leg or attack some other way. But none of these work out very well against someone who knows what he's doing. I also encounter the same problem when using the instep guard, or shin to shin guard. By the way, this is all for no-gi, as with the gi the friction makes it harder to just slide your knee out like this.