We bought an English saddle, but didn't know what size girth. So of course, the one we bought was too short! This extended was an economical fix for our "plus-sized" (as the vet describes her) horse.
Tessa didn't need and couldn't use one size bigger girth for her extreme bloat when being saddled. This girth extender fixed the problem instantly. I use the girth extender to tighten her up to the point where I can take it off still only using her original girth for the ride. It was money well spent.