Color: wood color Material:wooden Size: about 53*12*30cm 10cm=100mm=3.94inch Package List 1 set * mechanical arm DIY toys Only the above package content, other products are not included. Due to the different monitor and light effect,the actual color maybe a slight different from the picture color. Please allow 1-2cm differs due to manual measurement. 1Wood material,eco-friendly and non-toxic,safe for use,Let the child understand how the robotic arm works. 2 Cultivate children& 39;s ability to use both hands and brain,Allows children to experience the fun of DIY. 3 Hydraulic transmission is a kind of transmission mode that uses the pressurized liquid in the closed system to transfer motion and power. 4 The mechanical energy is converted to the pressure energy of the liquid,and then the pressure energy of the liquid is converted to mechanical energy. 5 Push the piston rod of the cylinder by hand to transfer energy to water through the piston,Water pressure can be transferred to the mechanical arm through the piston rod of the small needle cylinder.