The cars are beautifully colored; my 2-year-old grandson plays with them on his own or with an adult, trying to unlock, lock, and connect them into a train. Great not only for motor skills and dexterity, but also for learning colors, finding the specific car (fire truck, ambulance), and for nice moments of shared play. The cars are freely accessible anytime; we put the keys in a box to avoid losing them and use them during shared play.