Well Ragnar likes it.
I use a regular bastard file.cost 6.95 in any hardware store in america.Oil it up put it in a plastic lure package like a gibbs package fold it up an slide it in ur lure bag.Better than stones it removes material fast an is inexpensive.Them Lure jensen one are just crappy files, nice an small but they don't get the job done.Plus u can get 4 of em for what that thing costs.