Comments about Redrock Redrock MicroFinder Loupe Accessory Kit:
Bought this to use for several video productions I'm doing with a 5D MK II and 7D. Primarily shooting on 5D, was disappointed by the off-set nature of the fit with the 5D. Can makeshift a piece to wedge the viewfinder up high enough, but does match the screen. It does however, fit ideally on the 7D. Because of needing to use a base plate it is not quick to release and re-apply. I would not recommend if you plan to switch between your viewfinder and LCD quickly.
Comments about Redrock Redrock MicroFinder Loupe Accessory Kit:
The version that I rec'd works great but you must use a base plate or ... to secure the mount to the camera. You will not be able to use the little hole pictured to mount with a 1/4 20 screw for hand held work. I am using a 5D MK2 so it could be different for your camera. Having it mounted via friction between a camera and a base plate allows for quick dismount when going hand held from a tripod.