Got a new battery for old MacBook Pro (mid-2009) and needed special pentalobe screwdriver to change out the old battery and install the new one. Tried ordering from Amazon, using three different suppliers, all sent wrong size screwdriver which would not work (MacBook Pro uses different size screws from anything else, it seems.)
The iFixit Pentalobe Screwdriver for MacBook Pro (mid-2009) arrived and the new battery was in and charging within 10 minutes.
MacBook Pro (mid-2009) has unique pentalobe screws for the battery mounts that are not used anywhere else in the universe, it seems. Very, very hard to obtain, unless you go to iFixit.