Bearing Steel whose assembly with screws and bolt is simple but tedious and time consuming. Takes a lot of space but seems very stable. Plastic wheels seem tiny and very fragile for wearing that size. Another downside, a black military style painting resembling emery cloth. Not recommended for silk garment. Finally, a summary but sufficient packaging if the screws and bolts are thrown were not in bulk. Imagine that the cardboard has been holed ... the customer is left with a bunch of junk tinkered with bolts and screws recovery.