50A Surge Protector, Boxed. Prevent Faulty Power At Rv Campsites From Ruining Your Electronics. Analyzes Circuits To Verify Pedestal Power. Identifies 8 Outlet Faults, With Indicators That Illuminate To Show Power Status. Convenient Finger Grip For Ease Of Use. For 4-Prong Plug Outlets, 50A, Cetl Listed.