The Faceplate is the component that flashes around the fireplace insert and covers the fireplace. The Faceplate for the HEI170 insert is available in two sizes: 29" x 44" and 34" x 50". The size you choose should be based on the opening of your existing fireplace. Choose the 29" x 44" Faceplate size if the opening of your fireplace is less than 29" x 44". If your fireplace opening is greater than 29" x 44", you will want to select the 34" x 50" Faceplate size.