This is a replacement firebox for our RealFlame fireplace.  After 9 years it finally gave up its last ember.  I must say the improvement was very noticeable from the minute we turned it on.  The moving flame and color selection was a huge improvement.  The heat output seems to be 30-40% better than the dead one, plus the fan has better velocity.  Minor issue is that you can see the heat coil glowing red at the top.  The old one was hidden.  No big deal as the improvements outweigh this issue.  BTW, Wayfair really rocked on the shipping!  It was delivered two days after I ordered it.  Way to go Wayfair!