The plastic frame balance bike is a type of balance bike that has a frame made of plastic material instead of metal. Plastic is a lighter material compared to metal and can be molded into various shapes, making it suitable for balance bike construction. The plastic frame can also offer more durability and resistance to rust and corrosion compared to metal. However, it may not be as strong as a metal frame, and the plastic material may not last as long as a metal under heavy usage. Ultimately, the choice between plastic or metal frame balance bikes depends on the child's weight and riding conditions, as well as the parent's preference and budget.