I was looking for a VERY specific diameter for my Tokina AT-X AF80-400 lens that I've had for years and never used it. (afraid of lens weight with no support.) I ball parked 80mm with a fabric tape and struck out. Calipers out measured 73mm. Many hours on Google taught me that most listings of lens mounts don't put the inside diameter! I found one other person looking sometime ago and found a Canon mount to fit but I had no luck finding it. Back to square one! I just stumbled on to this one with the measurements LISTED!!! 72.8mm should be perfect for my 73mm lens....right?? Well I ordered it (some of DSLRKIT stock is U.S.A. or Asia) 11 days later I got to try it. To my surprise it was loose tightened all the way. Calipers back out......73.22...DANG IT!!!! Anyway too close to give up. I cut a 1/2" strip of a microfiber lens cloth. PERFECT! Tight enough to keep it in place and about a full turn on the knob lets you rotate camera and lens.
I ordered the one with the quick release plate. It comes with the standard base mounted. Remove it to install the quick release. Well luck has it that the first time I try it in my Q.R. it's too SMALL and slips out! (Plate screw stopped it.) I hate Murphy!!!! I temp-fixed with a piece of card stock. Probably my cheap clamp.
In the pictures I loosed the clamp and exposed the lens name and model which is covered when properly placed.
I hope this helps someone else in the same pickle as I. WARD'S WORLD

Does not work.

This is the only lens collar with interchangeable foot that I found for the EF 70-300mm. The Arca-Swiss style foot allows mounting more securely with lower profile, which are very useful for panorama shots. However, they managed to mix up the order and sent me the version with the standard foot. I had to order the Arca-Swiss type foot again. I didn't bother to complain because I think shipping it back would have cost more than the foot. The reason that I gave it a medium rating is because of the paint. Since the foot is already black, I don't care if the ring matches with the lens. Of course the white paint doesn't match with Canon's. It feels like the spray paint one can buy from a utility store. Paint powder fell at the opening of the ring after first use. I should have blown it with a blower first. They should really have done a normal black anodized version, instead of painting it white.

It is compatible, but only marginally. It's cheap to buy, so that's what it is. What's wrong with it? The hinge mechanism interferes with the rotation of the lens. The hinge contacts the small screws on the lens that serve to index the standard Canon tripod ring. On my 100-400 lens it barely rotates 80 degrees. I suppose you could remove the screws, but since they represent the stock configuration, that is not something I am willing to do. When the unit rotates, it sounds like it's scraping the paint off my lens. The thumbscrew is pretty rough when tightening due to paint the threads. A daub of grease fixed that. But do you really want grease near your expense lens glass? This is going in the trash.