This is a pass I learned very early on and has been very effective for me.
The traditional stack pass can be difficult no gi because of the lack of friction. It can be hard when fighting the legs pushing you away or securing a shoulder grip, especially if the opponent is sweaty and slippery.
In this pass, the goal is to connect to his lower back so that his legs can’t push into me.
Pinning the knee also makes it very difficult for the opponent to backroll out of the pass.