Depends what you want it for. The pitboss is perfect for street/trails, but if you want him on the track it's got to be the 18" micro. They are like rocking horse sh*t to find, and you only ever see wanted adverts for them, but there is actually one for sale over on bmxtalk at the moment, I can't believe it's not sold. My daughter is 4 and she rides one, she's raced it a couple of times and they really are the perfect size track bike for the little 'uns. Only problem is the tyres are expensive and hard to find, on the plus side though they hold their value (as you can see by the one on talk).