CL3 is typically better insulated than CL2... but monoprice is only pulling up CL2 for me.
I'd opt to get the best insulated and shielded cable, so CL3. And if you can, make a conduit (if you need to meet code) and run the wire through the pipe.
It is probably overkill, seeing as that 12/3 is held in place on the side of 2x4 with plastic nail down staples