I have used these double Western saddle bags with an endurance saddle, as well as an English saddle.
They have a breast strap for the front (variable from 28" - 56", it was too short for the chunky 16'3hh I used it for, so I tucked the strap into the saddle bag) and straps to attach to the front D-rings on the saddle, plus straps to attach to the girth.
The size is quite generous:
12" long 10" wide 4" deep
Total length (from bottom of one side to the bottom of the other side): 40".
