This fuse looks like a one time fuse when the current draw is to high it trips and causes an open circuit. There are resettable fuses as well such as this: VapeSafe2 Resettable Fuse : VapeNY... New York's Choice for Electronic Cigarettes, VapeNY... New York's Choice for Electronic Cigarettes
A one time fuse can not be reset and so once it has operated its a throw away.
Either a fuse or a kick is a good idea in a mechanical mod as they give an extra level of protection.
That is indeed a fuse. It is a measure of protection for you and your mod
It's a fuse to stop current flow if you have a short. Found the same one here. Yes, it's very worth using. It's magnetic and will stick to the battery. They say to put it on the positive or negative terminal of the battery. In the K100 I would use it on the positive end and put that end in first always.
Thanks for the quick replies, once my battery is charged I'll make sure to put the fuse in with it. Also, since my carto is ruined, how do you determine what ohm coil to use with a mech mod? I know it's based off of voltage but with a 3.7v battery a 1.8ohm coil made things taste off. If anyone can link videos or threads that could help please do.
Also, thanks everyone for being friendly and answering my dumb questions. This is making vaping and avoiding mistakes that much easier for me.