Dremel query - urgent!

Hi, all.
A really basic question: How do you use the sanding bits for a Dremel? I slip them onto the rubber cylinder, but they don’t grip it at all, and when they come into contact with the object to be sanded, they simply spin around.
Greatly appreciate any help!

Well first, there are two sizes, 1/2" and 1/4" these are the samll drum style rotating type. When you get the correct size on the correct size rubber drum ( you should have to push really hard to get it on ) them put the small screw into the collet and tighten That’s It.

Tighten the screw on the end of the rubber drum. This compresses the drum, making it expand to grip the sanding disk. When you’re sanding plastic, remember, a little goes a long way! Take it easy and chew off a little at a time. You don’t want to melt the plastic.

Tom