BV & Jo MACRO EXTENSION Full Set TUBES Fits CANON EOS SLR & DSLR,1D 1Ds 7D 5D 10D 20D 30D 40D,50D,60D,300D 350D 400D 450D 500D,550D,600D,T2i,1000D,1100D Camera DSLR.

Great product - allows you to shoot much much closer! Of course you lose autofocus, IS and aperture control (although depth of field button trick fixes this last problem - see other reviews), but for a tenner (and that's with delivery) it does a great job.
If you want a serious tool for macro photography, then this is probably not a product for you - using it all the time could get a little tedious, but for an occasional shoot it works just fine. To get a decent DOF you'd have to stop the lens A LOT, so the exposure time goes up hence a tripod /some sort of stabilising device eg. desk, floor ;)/ is pretty much a necessity. Also if you don't use one, focusing will get tricky/impossible.
If you're not sure macro photography is for you, but want to try without spending a lot on a macro lense - buy this! You won't regret it!

It does work, it is very cheap and serves its purpose so long as you know how to remove it without damaging your camera. There are a number of internet searches to help lines from those ywho couldn't figure out how to get it off and others have even reported costly repairs. A simple piece of paper advising to slide the knurled knob away from the camera body would save all that irritation and would justify a higher rating for an effective simple bit of kit.

I agree with what most of the other reviewers have said. For me, it's 5 stars for the price and 2 to 3 stars for the product, so 4 stars overall given you buy this in the knowledge it's not top-of-the-range. You can't argue with the price, something this cheap is in the "use once" or "try it to see if you like it before buying something more expensive" bracket. About the product itself, I have a little more to say...

As others have reported, the ring on which you secure the lens is very tight. I've certainly not had the problem of getting lenses stuck to it though, simply twist until the lens is tightly fitted and if it doesn't lock in (which my lens doesn't) then it will certainly be secure enough to hold the lens in place and not let any light in the sides. The other end of the tubes, the part that attaches to your camera body, fits perfectly on my EOS 450d.

The tubes offer great flexibility in magnification with all the various combinations you can attach them in. It's probably too much choice actually, having a couple of rings would be ample for something in this price bracket.

Photographic results are great. Extension tubes have no effect on the quality of your camera output since they contain no optics. Hence, starting off with a cheap set is a decent idea. You are, as others have reported, unable to use any of the electronic features of your lens once the tubes are attached. OK, so lens stabilisation would still work but you would be heartily recommended to turn this off in favour of using a tripod and remote shutter release (or timer) for such detailed work. You can't change the aperture of the lens with the tubes attached which is the real drawback of this product, but again you buy them knowing this will be the case. Again, as others have reported, there are (not recommended by Canon) ways of locking your lens aperture before you attach the tubes. The other electronic lens feature you will have to do without is autofocus, but that's no big problem, you'd probably be better off with manual focus at this sort of magnification anyway.

In conclusion then, clearly not a professional level product, but definitely recommended for the enthusiast on a budget who is just seeding their macro talents or someone who only occasionally might want to take more highly magnified macro shots than are available with their standard lens.