The Over Under pass is a pressure pass that is typically executed from the half guard position. It is a high percentage pass that is used by many top grapplers to great success in high level competition. Bernardo Faria is the most well known over under passer but many others such as Rodolfo Vieira, Murilo Santana and Lucas Leite all have a version of this pass in their game.
It is named the over under as one of the passers arm placed is under their opponents leg while the other arm is over the other leg. Once the position is secure you apply pressure by driving into your opponent and walking around until you can step into the side control position.
The Over Under pass is easier to complete in gi Jiu-Jitsu as the gi provides friction and grips that assist in the transition to side control. It can be performed in nogi but it is more difficult to complete as the absence of the gi allows the opponent to scramble back to guard easier.
This pass great for people who may be a bit older and lacking an athletic advantage over their opponents. This is because the pass is slower and more mechanical when compared to many of the more popular modern passing methods such as the toreando pass. The pass also complements the deep half guard very well as you naturally find yourself in an over under position after performing a deep half sweep. Watch Bernardo Faria to see this.
Here are the best videos detailing the pass along with some key details and other options from the position:
Strong pant grip under opponents leg with your over hand grip
Strong grip on top of opponents pants/belt with underhand grip
Stand on toes to increase pressure into opponent
Be patient before moving to side control
Pass being successfully implemented in live competition
The sneaky Kneebar
There is a option of a kneebar for when you start getting comfortable with this pass. This kneebar is very sneaky and opponents are typically not expecting it. This means that you need to be careful when executing.
In this video Bernardo Faria perfectly demonstrates this technique: