These are adaptors for fitting a lens filter of one size onto a lens of a different size.It is possible to get perfectly acceptable standard UV, polarizing or effect filters cheaply enough that you can just buy one for each lens - I have a UV filter for each of my lenses - but there are some quite specialised filters that cost a lot to buy. If you not made of money then this is a good way to be able to get the most use out of them.The rings themselves are very solid and fit very well on all the various sized lenses I have for my Canon SLR, with no wobble at all. In theory you could use all of them together to fit an 82mm filter on a 37mm lens, or vice versa. I'm sure that wouldn't be a great idea, but for stepping up or down one or two sizes this is an ideal solution, and a lot cheaper than getting very expensive filters that you won't use all the time in multiple sizes, just in case.For me, this is something that will not be needed very often, but when it is needed it will be really useful, and I think the price is about right for that sort of thing. I owuld not want to pay more for something used so infrequently.This product was supplied free by the manufacturer for the purposes of reviewing,