mounting aid

Have any of you seen a gimmick which would keep your saddle from slipping when you mount? If I recall correctly,
it is made of webbing which would fasten to the off side of your saddle and go around (under) the horses
off foreleg. I am sure there is more to it, but was only browsing when I came across it-and now, of course
it is forgotten. Once you are mounted, I think you can unsnap it and it would/could just go around the
horse's neck until your ride was through. Would appreciate your help. Thanks