I got these for my home climbing wall as a starter pack that has everything you need before going out and buying really specific holds that you're missing.
Large:
There's a good variety of a few big holds that allow 1 or two hands or even enough for a mantle.
Medium:
Some great and some "bad" holds in the medium range to practice 1-hand, finger, and crimps.
Small:
Then a bunch of little foot guys.
I used these on my wall which is a cave with a flat wall, a 30* overhang, and then a ceiling. They screw in with #8 screws (#9 is too big and will eat the insides of the hold).