Do NOT get this ripoff.
Several $5 cores, a couple of plastic followers that come in a $8 repinning kit (with more pins than this comes with), and a $30 cutaway is not a good investment.
Bets on how long before this vendor to starts to post astroturf comments on this like they've done on all of their other drops?
Bookishpick up a half inch wooden dowel, a small chainsaw file and a few cores from your local hardware store (a real one, not a big box) and give them a couple of extra bucks for a small baggie full of the pins and springs they'd use to repin them. You're gonna be out ~$30 and have more to practice with. You can pick up a foot of half inch OD vinyl tubing too if they sell it by the foot.
Cut the dowel into ~3" lengths, and use the chainsaw file to cut a groove into one end. That'll help you align pins and springs with the bible when re-pinning non removable top cores. You can also cut a variety of notches into the ends of other ones to deal with various cores so you have a follower for anything you need.
If you don't have a proper hardware store, the big box will sell a ~$10 repinning kit that will come with a plastic plug follower for the pins, and you can buy a core there too, although you might need to ask a sales minion for it.