I tried this on some pistol cartridges and it did make a difference in how they cycle through the press although, with the right dies I'm not sure it's worth the extra step.  For rifle cartridges (which I don't reload) I think it's a lot more useful.  Hornady makes good stuff.  Some of it is a bit pricey but I've never been disappointed with any of their products.  Don't expect one of those big jumbo cans if you buy this, it is a small can.  I'm guess it's about 1.5" - 2" diameter and maybe 6" - 7" tall.