This back brace is made by Meuller Sportswear, and is relatively easy to find in sportswear shops in the USA. However, it is very hard to find in the UK. It contain metal rods, and in my experience it is far more effective in helping you to sit well than any other form of lumbar back support. If you struggle not to ‘wiggle in the middle’ when you sit to trot or canter this will help you to find a form of spinal stabilisation that you did not know existed! It often works best as a ‘front brace’ (as shown in the photograph). I have also used it as a ‘side brace’ for people who struggle to find ways of not collapsing to one side. Although shown in use on my riding simulator I also use this in mounted lessons.
One size fits all.