I was a bit apprehensive about choosing these fuses due to the price and some safety concerns. Since then I have become his sincere supporter. I buy a few of these, some to replace circuitry in my HVAC lines that are "blown" with some regularity. This made it much easier to find and eliminate the root cause! Note: They are NOT a solution for situations where fuses regularly blow. This points to a more pressing underlying problem, but they can be good solutions for troubleshooting electrical circuits, or circuits that occasionally experience an unusually high inrush current draw (e.g. due to start/stop due to a mercury thermostat).