All pieces of our STEM toys are made with non-toxic ABS materials. To ensure kids play safer and reassure parents. Parts of stem toys are smooth without burr and precise assembly with a high degree of integration. Clever structure design makes multiple parts common and kids will love it and refuse video games. DIY toys: DIY building block includes simple fastening screwing assembly and simple wiring to complete assembly. To train kid's ability to think independently solve problems with hands and brain Manufacturered by Alphabet Robot. Climbing engineering vehicle: This is a 4WD car modelchanging the rivet positions in the angle adjuster will change it's heightand climbs over obstacles up to 50 mm with easy. DIY Climbing Vehicle are 2 power modes: battery power and solar power. (The kit isn't including battery) Our STEM 4WD car assembly toys can help children master the principles of energy transformation & mechanical movement structure on their practice. Child is trained to be a scientific explorer.