This is a beautiful NEW dressage saddle, although it has been consigned. It has an 18ins seat with a medium width fitting: See stamp.
The WB4 has a deep seat with the lowest point of the saddle more towards the back of the saddle. This type of saddle is frequently used on horses that are long-backed, built downhill, or have a very straight shoulder. This model reduces the pressure on the shoulder and makes it easier for the rider to ask the horse to come more forward with the hind legs. It is also an appropriate saddle for large horses.