Sensei Erik Paulson demonstraits two finishing holds based on how you catch the Thai Round Kick. Catch A (or Overhook) is followed by an Achilles Tendon Hold, A Foot Lock and then a Heel Lock. Catc B (or Underhook) is followed by a Straight Knee Bar

Demonstration of an double leg takedown initiated from an underhook

techniques vs the double underhooks clinch

Takedowns from the single underhook for mma training