Offered Christmas for my 6 year old son. Very nice surprise! I chose this tour for its price (under 30) and its wheelbase ground (smaller than most). The installation booklet is very clear. It reminds those Legos (at each stage the parts to be added are listed before e ^ be put into position on the circuit). My son was able to ride his first model (the # 2) and one already created one. It is obviously confronted with the law of gravity, but therein lies the charm of this toy: refine his setting so that the balls are gaining speed, but not so rails have ... ale ale ... not easy but he likes to do the mechanic adjusts his work. The overall strength of the toy is in principle correct, but with kids a little "nag", the case seems inevitable. Once running, the movement of the balls is quite fascinating (type pendulum bearings). I was particularly attracted: one feels well thought product (the pieces "balls" are used ingeniously to create any type of angle), the elevator's chain is up link by link: interesting to understand operation and to customize its size to personal montages), ease of installation (they are clips ... by cons to be careful when you ruined the circuit), the number of balls provided, the 'softness' of the motor ( my son certainly would not agree with me ;-) but it induces the rotational movement is soft and especially very low-noise: It can play without any worries during the nap of these brothers & sister ... less : certainly the fragility of some pieces ... Note that I recommend for older children or for those (like my son) who are experienced in the ... technics lego game mechanism are different but the approach remains similar which facilitates the handling of this toy autonomy.