Where and how to disconnect the battery

Battery Disconnect Switch 12V Master, 12V-48V Waterproof Battery Shut Off Switch, Heavy Duty Battery Isolator Switch, 275Amps High Current for Car Marine Boat RV Vehicles (On/Off)

Kohree Battery Disconnect Switch 12V, 12V-48V Battery Isolator Power Cut Off Master Switch Waterproof Marine Battery Switch for RV, ATV, Car, Marine, Boat, with 4 Mounting Bolts, 275 Amps, (On/Off)