The open petite (about 5” opening) is for broad shoulder horses with little to no wither.
The open extended (about 10” opening) is for broad shoulder horses with above average to high wither.
The saddle needs to fit really well to do an open wither 9 out of 10 times we’re going to recommend the regular and just adjust the contour.
The gooseneck contour curves up and over the withers for added wither clearance.
The deep contour curves up some in front and some in back, ideal for horses with butts higher than their withers.