My 2009 MacBook Pro replacement battery required a Pentalobe screwdriver.
I thought that putting in a new battery would be simple, but that was wrong. First, it was hard to find an OEM replacement battery that was legitimate. eBay has lots of fakes for sale, and there are plenty of horror stories of using these. Apple won't sell you a replacement battery - but they will do a laptop repair. I wasn't happy with this option. I finally found what I thought was an okay battery only to discover that Apple used another unique screw to prevent battery replacement. I found a number of pentalobe screwdrivers for sale but the prices were generally high for just one screwdriver. The iFixit 54 bit kit offered a much better value for a screwdriver, although the overall cost was higher - so that's the route I took.
The repair was a snap. A couple of minutes and the new battery was in. It really couldn't have been easier.
I was very happy with the iFixit bit set. My only complaint was that the design of the plastic case keeps it from really closing the way it should.