Package:300Pcs Toys Wheels and 150Pcs STEM Shaft Material: PP and metal;Main Color: Black;Blue;Green;Yellow(You can freely choose the color you like). STEM shaft size:2mm(??)X100mm(Length)??Suitable for STEM Toys RC model cars toy DIY Plastic toy wheels size:Shaft Dia: 1.95mm/0.08″,Suitable for 2mm shaft. Diameter: 30mm / 1.2 “. Tire width: 8mm / 0.31 ” 100% new products,Sold by EUDAX,And responsible for all after-sales,If you have any questions, please contact us for free and we will do it for you 100% satisfaction. -Length 100mm/3.9″ -Diameter 2mm/0.08″ Package include: 300 x Plastic Toys Wheel(30mmx8mm) 150 x STEM Shafts(2mmx100mm)