I know this sounds like a stupid question but, how do you put on a kilt pin?

Does it go through only the top apron or do you pin it through both top and bottom to hold them together so they don't open up?

Also, is there a specific place you are supposed to put it? High, low, middle?

I have seen some clan badges that look like they would make a nice "pin" instead of an actual kilt pin.

Larry