How to throw a rear hook
The heaviest hook you own — the rear hand swings across the body with the whole rear leg behind it.
Action
The same arc as the lead hook, but driven by the rear side: push off the rear foot, pivot it hard, and let the rear hip and shoulder carry the fist around in a horizontal line toward the jaw. The lead hand comes home to protect your own chin while the rear arm swings — for a moment your face is turned toward the punch. Recompose the guard the instant the fist passes the target.
When to use
When the opponent circles toward your rear side and walks into range, or as the second power shot in a combination: 1-2-4 and 2-3-2 are the classic patterns. It is also the standard answer to an opponent who slips your cross to the outside.
Advantages
The most power available in a hook — the rotation has the whole rear leg and hip behind it, and it lands from an angle the guard rarely covers well. It is the punch behind many of boxing's most famous one-punch knockouts.
Limits
It has the longest path of any punch, so it is the easiest to see and the most expensive to miss: a wide rear hook leaves your entire right side open. It also needs the opponent at exactly hooking distance, and the big rotation must be reset before you can punch again.