These are the only socks I buy for my 2 boys, and I have been buying them for a couple of years now. I have the gray bottomed ones for one son and the white ones for the other, since otherwise they'd be really hard to sort. They are only 1 size apart. The sizing is SOCK size, not shoe size. You can find a good sizing chart for this specific brand online.
Unlike the floppy Hanes socks that my sons hated, these are nice and snug fitting to the foot. They have a good padded foot bottom too. They have lasted and lasted and lasted. There has only been one sock in the two years that they've been wearing them that has gotten a hole in it. My boys will occasionally sneak outside without shoes on too, so they are hard on their socks.
I have also bought the low cut version for the summertime, which is great when they have to wear sneakers.
I cannot recommend these socks enough. Try them - your boys will love them!