We love snap circuits. We got DS5 snapcircuits 100 when he turned 4 because we thought he would like them...he LOVED them so we ended up getting the upgrade to 300 for Christmas. Of course...now he wants the 500 so we may buy the upgrade kit for that for his b-day or something. Should have saved money and just bought the 500 at the beginning but we didn't know how big of a hit it would be!