Seat size is measured English and typically 2" more than Western.
The western skirt was redesigned to have incorporated panels for a slimmer, closer contact feel. It comes with the Western saddle, but can also be added to the Florac, Quevis, and Quilty models for a western look.
Rave reviews for this option - "Had my first ride today and OMG it felt so good! Horse was comfy and she moved out really well. I never liked the velcro panels as I felt like I was hovering over the horse. The western panel/conversion distributes everything well without losing the close contact feel. Winner winner! Thanks for your help! The sheepskin seat cover is comfy too! -Gabe"
Note: if your horse is narrow or downhill and shimming might be necessary for rider balance, the best option is the "pocket shim" that goes between the skirt and the base. Ordered here.