Ease of installation! Also, both outer glass doors and inner screens are cabinet style and secure strongly in place magnetically!! Cabinet style doors are so much better than the old bi-fold doors I had. Im happy with this product at this point with the installation  just completed but still need to see how it performs when a fire is cooking. 
Should also mention that Wayfair had it delivered a day ahead of schedule!  I particularly liked how I received text messages from Wayfair while waiting for the shipment to arrive, especially the text that it had been delivered!! Not a bad experience I must say with this being my first purchase from Wayfair. Will definitely continue to shop Wayfair.com!!