I bought it  3  years  ago. It works  really  well, but you  need the knob and it is  very annoying that  when the surface is wet  the stove stops,  marks and  error and  sometimes the breaker goes off. Don´t  let  the surface get  wet,  don´t  try to clean it when is warm   even  removing  the  lead of a pan, we have this problem. Looks really nice, and it is  very  flexible to  use  with  a lot of pots and pans at the same time.     Actually  Im visiting the  web page  because   we do need the knob!