Oh yeah its a saddle seat saddle. Looks to be of equitation style (deeper seat). Does it have any tags under the flaps where the stirrup bars are located?? Usualy suede seats in saddle seat (aka Flat saddles) are often seen in lower quality India or Pakistan made saddles. Whitman, Lovatte and Rickets, Barnsby, Shivelys and etc usualy do not (they are high end flat saddle makers)at least I havent seen it yet. Gold Winner, Silver Fox and Equiroyal are India made saddles and are low quality you can buy a new one for 300.00 some even with girths attatched. They don't hold up well. I have a Gold Winner saddle that I bought for 50 bucks damaged, simply so I could learn how to do such repairs without fear of further damaging the saddle. Even repaired its still only worth 50 bucks. I use it occasionaly and its actualy is comfortable to sit in but quality its not. I can't even dye the darn thing due to the shellac they used on the cheap leather and I can't get it off either. It wont absorb oil and it feels like cardboard. All signs of poor qualilyt leather. (I mean in India Cattle are worshipped not turned into saddles.)
It (the seat) looks larger than 18 inches but pictures can be deceiving. Measrue from the pommel button straight back to the center of the cantle and that should give you your measurements.
I like a suede seat gives a little more security and you can find them on quality saddles just not typicaly on flat saddles. (some polo saddles of good quality have suede seats).
"The question is not, can they reason? nor, can they talk? but, can they suffer?" Jeremy Bentham