Attached Link: http://www.cokin.fr/

I have not had a problem with glare and not heard of any, they do a lens hood which also fits into the holder should it be a problem and a lens cap if you want to leave the filter holder on the lens/camera. The holder takes 3 filters [or accesories]. I have slotted that warm filter into the slot furthest away from the lens in this pic. but of course you would use the one nearest to the lens first in reality. It is a very versatile system: the front twists to angle the grad. and the filter slides up and down so the graduation can be accurately set on the horizon or for the warm up filter slot it in upside down and just warm the foreground without affecting the sky. I like the idea too that it is only buying another size holder if you want to fit it to another size lens - you havn't got to buy a set of filters for each lens/camera. With ND Grads. I have the ND2, ND4 & ND8 but of course I could have combined the ND2 & ND4 to make an ND8 so it is not entirely necessary to have all of them, same for non grad. ND filters. They do a polariser and many other filters all to fit the system, not sure how it is in US but here in UK there are quite a few people making third party filters which fit in the holders of the major manufacturers. In use I set up the shot composition with just the holder on the camera then press the exposure lock button and slide the filter in. This then shows me an accurate image on the lcd of what I am going to capture and it is easy to see where to position the filter because the cameras exposure meter is not trying to compensate for the new scene. See link for what I have but there are other makes.

And every one said, 'If we only live,
We too will go to sea in a Sieve,---
To the hills of the Chankly Bore!'
Far and few, far and few, Are the lands where the Jumblies live;
Their heads are green, and their hands are blue, And they went to sea in a Sieve.

Edward Lear
http://www.nonsenselit.org/Lear/ns/jumblies.html