Surely this cannot replace practicing out of a well maintained sand bunker?

We believe Pocket Bunker is even better than practicing from a sand bunker. It breaks the bunker shot down to the basic requirement – miss the ball. It gives the user some time to practice in private, taking the stress out of public failure. It is also less forgiving than a standard bunker shot, so whether you hit it thin, fat or shank it, you will see it from the response. If you can play the Pocket Bunker well, bunkers will be a breeze. It furthermore provides a lasting image as reference when in a green-side bunker.