There are tons of information on the web. And because there is so much, we have not replicated what is already out there. The links to the left show how similar devices like the GUARD are connected and work on a real penis. The DTR specifically emualtes the attachment method of GUARD. Those links depict the principles for trapping and stretching the shaft skin.
GUARD follows the same principles, except you control the tension, exactly.
All foreskin restoration devices follow the same basic skin trapping idea, it's how you go about implementing that idea that counts.