later These DC switches are very useful when building circuits. They act as a safeguard against overload etc., but can be reset by pressing a lever. The lever also serves as an indicator for the operation of the gas interrupter. I try to buy switches for about 20% more than they protect. Fuses are more accurate, but I've found these switches to be good for general purposes. My lifepo4 batteries have normally never dropped below 20-30% charge but on one occasion they did. My charger was working hard to charge them, but it was almost 100 degrees Fahrenheit outside so it was overcharging. The 100 amp switch I had on the outlet tripped and saved me from disaster. Let everything cool down for a few hours and charge overnight when it's cooler. No problem. The fuse would have blown too, but if I didn't have a spare I wouldn't be able to charge my battery.