This palm rest does not slip and is very small. In order for the mouse hand on the table is fairly fixed. If you change your sitting position, you have to reposition the pad is usually because the hand has it no freedom of movement. Mir is also the support way too hard - but that's probably a matter of taste.
Why the support is in two parts (base + pillow), she will not reveal to me. In this I see no advantage. For me a clear misconstruction. The Fellowes wrist rest is much more comfortable!