When you look at a seat collar, it 'squeezes' the frame (for lack of a better description). With these rings, they're completely against the seat post itself. Secondly, it's similar to having two nuts on a bolt. These are in addition to the seat post collar, so it's like a backup system, except that these are stronger than the collar itself. Hopefully that answers your question.
I sent Mudda a PM about this, but I have a small bike parts company (www.chasebicycleproducts.com) and we now have a Seat Post slippage solution It's a simple lock ring that sits above the seat collar and stops the seat from slipping back into the frame. I've got them in 27.2mm and 31.6mm sizes and they'll work with carbon or aluminum posts. They weight only eight grams. Please let me know if anyone is interested. They would be $12 including shipping to South Africa, or anywhere in the world. Dan Chase Bicycle Products
