When purchasing Norton or any other brand from eGoods365.com store, you can be sure that (a) you are purchasing from US based company with the most responsive and friendly customer service; (b) an authentic, not a counterfeit and not a refurbished product.

Fast cutting, aluminum oxide stone, six inches long and one inch
square, lets you make a long, steady stroke and turn out those
glass sharp, silky-smooth trigger jobs that make shooting a joy.
One inch square size offers excellent steadiness and good
visibility. Lubricate with stoning/honing oil. Excellent for many
other stoning jobs too. MF-76 Medium is perfect for fast
cleanup of manufacturing burrs found in most new guns. A few
quick strokes in the jig results in a much smoother trigger pull.
FF-76 Fine offers an excellent combination of speed and
smoothness of cut to put a final finish on trigger parts for a crisp,
smooth, trigger pull.