This is a hip isolation / knee submission. This submission is accomplished when your opponent posts his leg while you are in side mount in an attempt to prevent your pass into mount. Note: Even though hips are isolated with a half lockdown maneuver, keep your base low as it's good practice when fighting against opponents larger than you are. Stay in control.
Seth is in side control and his opponent has posted his leg in an attempt to keep Seth in side control and preventing a mount.
Seth bumps his opponents leg with his knee and forces the leg down with pressure on his opponent's ankle.
Seth will pass into a modified half mount / half lockdown maneuver where he will feed his leg over the isolated leg and through the bent leg. This secures his opponents hips and prevents any effective bridging
After securing the half lockdown maneuver, Seth will keep a low base and reach for his opponents open ankle. Use of a monkey grip is preferred in this position for control. If the opponent is resisting heavily, view Image 6 for an alternate finish.
Seth will pull on his opponent's ankle to apply the submission. Keep your hips low to the opposite side of your opponent to prevent the possibility of being bridged off. Keep in mind, even though your opponents hips are isolated in this technique, you want to continue to keep good habbits and be prepared for instances in which you may be fighting a larger opponent.
Image 6 (alternate finish)
In this image the opponent has resisted the initial submission attempt. Seth will transition to a knee on belly mount and pull the isolated leg upward to focus more on a knee sepparation submission *(when practicing this submission, keep in mind that if you were to fall back on the knee on belly with control of your opponent's ankle you will still apply the correct leverage needed to finish this sub. Be careful when training this submission to ensure the safety of both fighters.)*