18 Gauge Outdoor Burial 18 Gauge cable for outdoor cable installation underground cable, Shielded and Non-Shielded.
The SHIELDED cable is for the maximum noise immunity.
Stranded 18 Gauge cable use it for Security and Sound Systems outdoor.
If you have a choice and can put the shielded cable into your budget then you should
consider it over the non-shielded one. Both types are good but the shielded has that extra layer of protection.