Product review (1 stars): Metal on the outside, fragile plastic on the inside.
These are metal on the outside, they even have a metal backing plate. However, that's where the patina of quality ends. The inside is made of a poor quality and fragile plastic. Check on line, Samsung regards this as a cosmetic problem. After around two years they crack down the sides and become loose on the stems. They can be toughened against this failure by sleeving the plastic core with a stainless steel hose clamp, the 2-ear type work well. Two years is nothing for a stove and I really don't like the idea of paying 1/5th of the cost of the stove every two years to replace these crummy knobs.