" Automatically shuts down power during overloead or short-circuit conditions"
Overload.....high amp draw
Short-circuit....ground fault
"WFCO ULTRA III Distribution Center"
It is protecting itself.......not the rest of your appliances, electronics, circuit boards etc. due to High/Low Voltage excursions, Open Neutral, Open Ground, Reverse Polarity, 240V , Frequency Excursions AND Surges.....like a quality 'surge guard' will.
Are they needed.......NO
Are they worthwhile tool to have.......YEP.
Sorta like Insurance.....have it and hope to not use it. BUT one 'OH #^#%$' and $$$$$ replacing appliances, TVs, circuit boards.
Best one....Progressive Industries Surge and Voltage Protection in 30A & 50A (More important with 50A rig) PLUS lifetime warranty.
The other brand........1 yr. warranty