This is absolutely a brutal pass of the half guard that someone can execute, and if you have never been the bottom guy whose lapel is wrapped behind his back, you better experience it soon so you know exactly what must NOT happen when you are the bottom half-guard player.
It is absolutely brutal, immobilizing, and almost helpless position, where the top guy dictates everything, and tapping out is pretty near the corner.
Leonardo Leite beautifully explains this technique in this short video, as well as body positioning during the pass – whether it will be to a side position or to mount.
We cannot recommend this video and technique enough! It is absolutely effective when attacking (if you do the thing with lapel correctly), and if you are the bottom guy you must do ANYTHING to prevent the top guy from pulling out and using your lapel against you.