i used the same caddy, except I got it from e-bay.
At first it would not fit precisely into my 2012 MBP, which I thought was odd.
Upon further inspection, it had a bit of a black bumper on the side where the disc would slide into the optical bay.
I proceeded to remove all screws from the tray, and pull the black bumper off. It then fit like a charm.
Not sure if it was like that because it was originally meant for something else, but closing in on a week now and it hasn't caused any problems.
At first it would not fit precisely into my 2012 MBP, which I thought was odd.
Upon further inspection, it had a bit of a black bumper on the side where the disc would slide into the optical bay.
I proceeded to remove all screws from the tray, and pull the black bumper off. It then fit like a charm.
Not sure if it was like that because it was originally meant for something else, but closing in on a week now and it hasn't caused any problems.