Bought this to go under an indoor/outdoor rug.  It was a bit wider than the rug by several inches, but very easy to trim down to the right size with just a pair of scissors.  It adds just a bit of "give" to the rug, which is good since it's on concrete and could really be hard otherwise.  it's a large rug, so I didn't anticipate it slipping much anyway, and it hasn't.  The pad was just to give the rug some sort of backing, and it does that very well.