The plates are fine. Cast iron.
The bar is fine. Cast iron.
The nuts to secure the plates are plastic. Not ideal but can be lived with.
The handles themselves that sit between the plates on either side on the other hand? Such poor quality material that if you secure the plates with any semblance of tension it warps the handle inwards. The honest truth is I bought this product but had to use the plates on old dumbells I managed to scratch together I already owned.