I wouldn't recommend this ligature. It's not quite big enough to fit around the Windcraft Alto Sax mouthpiece and hold a reed in place without slipping.
The supplier responded:Hi, we're sorry it didn't fit for you and we can happily replace or exchange that for you. We do sell hundreds of these with the mouthpieces as well so we know they can fit fine, however sometimes after transit they may need a little re-shaping to fit smoothly. Once again apologies it wasn't quite right for you.