Yes, they are fab. My lil dumpy cob wears one cos she's got no withers and her saddle tends to slip. She's wore one for a few years now and her saddle stays put with it. They go in the washing machine too so stay sticky for ages
I use one of those as my mare doesnt like numnahs, they itch her.
I was thrown of in september and my foot was caught in the stirrup,and got dragged. The saddle didnt slip even a mm. Even with all my weight on that one side.
I love them and they are so easy to clean, just a quick rinse.
I keep meaning to buy one as I think it would really suit my horse's back. A friend has one and she says they are brillint. I did read something though that they can pull on the horses back but I think they are worth the money.