spring riders series, detaied information as following: 1. square plate and pring powder coated (Electrostatic lacquer ), stainless steel screw to fix foot plate. 2.plastic parts is made of LLDPE (linear low density polyethylene), which is colorful, odorless, innocuous,recylable , smooth and safe for kids. 3.It is easy to install in school, park, amusement park area etc. 4. it can strengthen their sense of balance,bring joy for children