The screws go through the grommets and into the screw holes on the sides of the drive. You should slide the drive into the bay, line up the screw holes in the drive with the grommets, and then insert the screws from the outside of the bay, through the grommets, and into the drive. Nothing could be simpler. The only care you need to take is to make sure that the thicker side of the grommet is UP. This means that on the upper side of the drive, the thicker part of the grommet will be on the OUTside of the bay, while on the lower side of the drive, the thicker part of the grommet will be on the INside of the bay. This should be common sense, but some people get it backward. Making that mistake will give less effective noise and vibration damping. The other common mistake is OVERTIGHTENING these screws. You want to tighten them until the drive is secure, but you do NOT want to tighten them enough to compress the rubber grommet. That leaves the screw head flush with the grommet. Nothing protrudes, so there should be nothing to prevent the the drive bay from sliding back into the case along its tracks.
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