My NN3 came with this:-

I had it permanently fitted to my Canon 350D, but alas I can't leave it on my new 550D as it stops me changing the battery.

The problem on the 550D (aka Rebel T2i) is the distance from the centre of the tripod socket to the battery door is 25 mm, but the distance from the screw to the edge of the CP-2 is 27mm, thus it blocks the battery door...

As a workaround I'll try get hold of the original CP-1, but is there a slightly narrower version of the CP-2 plate assembly available/in the pipeline?