More convenient than the traditional cast iron trivet and a lot lighter, especially if dropped. The iron ones can shatter or break a foot, as happened to someone I know - twice!
Of a size suitable for any pan, larger or smaller, they will protect a surface for several minutes. However, it should be borne in mind that some pans, especially those with a multi-layered base, can hold their heat far longer than a traditional single-layer pan, so could cause damage to the mat or the surface beneath if left for too long.
There is a hole to allow them to be hung out of the way, although perhaps a little small although large enough for the traditional metal hook, but you could loop some string through and hang from that.