It's a "chemical fuse" a fuse with a third terminal to trip it. It doesn't require as much current on the 3rd terminal, making it easier to trip. They are a big pain to find, like surprisingly so. You can use a chunky mosfet that can handle enough current to trip your fuse in the appropriate time frame, or you can use a thermal fuse (70-80c should be fine), and park a resistor next to it, so the resistor trips the thermal fuse.