It would be supremely helpful if there were something of known size included in the pictures, particularly the S/M/L pictures. Yes, there are dimensions listed and in a perfectly calculated world that's all anyone would need, but this ain't that world.
Help us help you help us. Post pictures that actually delineate between the options we're expected to choose from.
TomaCzarOne spec relative to size that mattered to me when I bought mine was which models accommodate the standard size of cut firewood you see bundled for sale outside most large markets, at least in the western U.S. It turned out the small and medium fireplaces weren't big enough, so I bought the large.
Help us help you help us. Post pictures that actually delineate between the options we're expected to choose from.