The size of the bracket is ok, holes are where they supposed to be. The problem is what another buyers mentioned already - the holes can not take different screws than the ones which come with the bracket. If you remove old hard drive from iMac, you can not use the original screws. They do not fit. The problem is, the screws which come with the bracket are short, and you can not fit them properly. I managed to solve this problem like this (this is about fitting in iMac 24" Late 2006):
1. Bottom screws - use the new screws, put them from inside of the frame, so the ends are coming out through the bracket.
2. Top screws to hold plastic attachement - I used double sided sellotape to attach the plastic bit and then I wrapped around the plastic and the top of the bracket with normal tape.
Final result perfect, but it could be so much easier, if the holes for screw are in the same size like the screws for the hard drive.
All this above sounds very complicated, but if you will deal with fitting drive into one of the iMac I am sure you will understand what this is about.