We have these building blocks used (with little contamination) purchased and plugged straight into the washing machine - fine stage, cold - and then they were like new and also the "chirping" in the laundry tower has survived. Our eight months old son has a lot of pleasure to examine the individual elements with different materials and noise, and he likes to turn push Mamas buildings. We suspect that these blocks are yet to be tested for several months, because children themselves form stack so until 2 years of age. What's great about this toy definitely, is the versatility and low risk of injury - I can leave with my baby in the playpen which blocks easy. The original price is added quite high, but the workmanship justifies it - can best give; )