We bought a house with a 20+ year old Royal 42" Heat and Glo Fireplace insert. It did not have glass doors. We tried and failed to purchase original manufacturer doors, then discovered the Brick-Anew insert. This product is perfect, and very simple to install. The frame came fully assembled. I had to remove the top lip of the Heat and Glo (4 screws) after which it fit in snugly. I did secure it with the provided 4 screws. Installed the small thin frame did not interfere with the fire place use, view of the fire, or the outside air holes in the Heat and Glo frame. We love it, and are convinced that it is not only giving us the comfort of knowing when we go to bed that sparks can not escape the hot bed (you have to let the fire die down before closing), and the closed doors with its tight seal is reducing heat loss up the flue from the house. I can not speak more highly of this product, or of the team that worked with me. I spoke personally with them to ensure their system would work with the Heat and Glo sharing both pictures and description of what I had, then when I improperly measured the metal spark screen they were quick to provide a refund. My only regret is that I don't have another fire place needing one of these inserts.