S-Mount is an amazing position for setting up attacks. Since this position establishes extreme control over your opponent, it’s a great position for specifically attacking arms.
Establish a high mount position on your opponent. Grip your opponents lapel, near their chest, as an initial set up.
Pull your opponents lapel with your left hand while pushing your hand along your opponents collar as deep as you can to establish the cross collar grip.
Move your let hand to your opponents elbow and push it down. While doing this, slide your left knee under your opponents shoulder. Keep heavy pressure and drive your chest onto your opponents arm.
Grab your opponents left elbow with your left hand or forearm. While doing this, circle your right left under your opponents right triceps area.
Drive your weight forward and tilt slightly to the right to help lighten the other leg for quicker movement.
Move your left leg over your opponents head and secure the armbar position.
Finish the armbar by maintaining control of your opponents arm and failing back.