While wiring requirements will depend on local building codes, CL3/FT4 cable is UL (fire) rated for residential and most commercial in-wall and in-ceiling applications. It's important because ordinary speaker wire, the kind you can get at just about any store, was never designed to run inside walls. If it catches fire, the outer layer shield could act as a fuse. Be safe and always check building code requirements.
A Word About Burying Cable Outdoors
Most folks will bury cable when running outdoor speakers in the yard. If you plan to bury the cable, we recommend you bury it 4-6 underground so that it's not visible or poses a danger of somebody tripping over it. We also recommend using CL3 rated outdoor speaker cable specifically designed for the outdoors. Our speaker cable can withstand extreme weather conditions like rain, snow, and high temperatures and incorporates twice the insulation.