The Head Inside Single Leg is perhaps the most universally used shot in combat. It works well amongst all weight classes, and even works with larger opponents.
Unlike a Double leg, which uses a good amount of strength to finish, a head inside single leg works almost entirely against balance. This is why a smaller opponent can use it against a larger opponent and find great success, as bigger people tend to have less mobility and balance.
My brother David has used this shot with great success throughout his career, and shows the classic finish, Running the Pipe. This is the go-to way of finishing the take down, that is often misunderstood as spinning quickly. Instead, you see it’s more about locking out the leg and putting pressure on the hips.