Quarter Horse Bar or Semi Quarter Horse Bar (usually 6 1/2" for semi - 6 3/4" for regular gullet) is by far the most common tree. It is for the medium back, decent wither and often mixed blood descent (1/2 Arab, Appendix or other mixed breed).
The FQHB tree (usually 7" gullet) is often used for the "Bulldog" Quarter Horse or horses with broad backs and sometimes mutton-withered Quarter Horses.
Arab saddles are for Arabians they have a shorter (usually 6 1/2" - 6 3/4" width) gullet.
Gaited horse bars have a higher gullet for high withered horses.
Haflinger saddles (7 1/2" gullet) are great for Haflingers or short backed mutton withered horses.
Draft Horse bars (8 1/4" gullet), are for the large Draft Horses.
*NOTE - The gullet size is determined from the raw tree. It cannot be accurately measured once the saddle is assembled. There is no industry standard to gullet sizes so a Circle Y qh bar is not necessarily the same as a Big Horn qh bar. Not only is the gullet width a factor but also it's angle and height. In general, a rawhide tree has a 6 1/2" gullet width and the wood tree has a 6 3/4" gullet. Often times, changing the thickness of the pad greatly affects how a saddle will fit."
Please call for more info on the saddles. I can send you pictures of other views on them. It cost approxiamately $60 to $75.00 to ship a saddle depending on destination, weight, and size of box. Thanks. 785-761-5900