Installing Piston Pin Clips (by hand or with snap-ring pliers)?

From JE pistons:

"Generally Tru Arcs are the easiest to install and are more popular in lighter duty applications. The snap ring or Tru Arc is easily installed using dedicated pliers. The tips of these pliers fit into the holes at the ends of the snap ring. When the pliers handles are squeezed, the snap ring compresses enough to firmly seat into the retaining groove on the piston. A word of caution: snap rings are manufactured with a smooth and rough side. Be sure the smooth side faces the wrist pin. Also, install the snap ring with the open end pointing down."

Not sure what they mean by smooth and rough but I will have to take a look at 'em.

Article:

Wrist Pin Locks: Different Styles and How To Install Them