Heavy gauge steel. Real rubber wheels. This thing turns heads man! Instructions are a tad hard to follow. Here is a tip, move your OLD shopping cart near you when you assemble this. Look at the instruction that come with your order, then look at that section of you OLD chart. The rest is cake. PS: If you don't need the old cart anymore, please dont just throw it in the garbage, give it away or put it where someone who needs it will find it.