eyecups for eyeglass wearers

ARRGH! finally tired of dirty, scratched glasses looking through the view finders of my cameras...I have read mixed reviews online of some of the products...some fall off and etc....anyone have a favored solution?

Canon 7d, 5d MkIII

Thanks

I use the one made by Hoodeye. http://www.hoodmanusa.com/products.asp?dept=1061

very good product. It does cover a small section of the top part of the LCD but not a big deal once you get used to it.

I second the Hoodeye product but make sure you get the one for eyeglass wearers. I bought the prior model a few years ago and my eyeglass lens would sometimes get smudges on it when pressed against the rubber of the Hoodeye. Last year I saw the eyeglass wearer version and purchased it. No more smudges---what an improvement.