Optivisor Advice Please?

Hi guys and gals,

I've been looking at the 'Optivisors' on amazon and i'm a bit befuddled as to what is good quality and what is not!

Can anyone recommend any of the following:

http://www.amazon.co.uk/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=optivisor

Any help in this matter would be appreciated :)

Darrell.