This trolley does not come pre-assembled; You have to screw the casters to the frame. It's fine unless you buy a lot of them, but you'll need an open-end wrench to tighten the roller bolts. The frame is made from high quality injection molded plastic that feels strong and durable. The wheels can all be swiveled and appear solidly processed. Solid rubber wheels are 4" in diameter, so they perform better than the smaller wheels when riding on rougher concrete or riding over wider seams or grooves. I bought it with three other carts (see my reviews) and it was the most expensive of the three. I use stacked plastic bags to move around (clear ones are available at Costco and other places). Plastic, they're ok if you need a cart that can get wet or need a wash (leave casters and fittings greased to reduce chance of rusting). If you need a general purpose indoor cart see you my other reviews. to cheaper alternatives.