Have you ever had a Keppeler Barrel Insert?

Does anyone have any reviews for Keppeler Shotgun Barrel Inserts? It looks like they make them to fit the full length of the barrel and that they can be adjusted to change the point of impact, if necessary and with out removal. They also claim that they can be inserted or removed without affecting the point of aim once its set. Seems way to good to be true, or else they are way out of my $$$ Ballpark and likely both. They advertise a plethera of rifle calibers plus special order. I've got all kind of pipe dreams running through my head on this one! Imagaine your fancy 24VD, 357/20 with the mint case color and the checkered up fancy stock, suddenly modified to 357 over 357, and both barrels shooting to the same point of aim. WOW! If you've got any info on these inserts please share.

www.keppeler-te.de/cms/pages/englisch/hunting/insert-barrels.php