"Slotted Patches On Backpacks"
"It's called a lash tab, and it's there for you to attach whatever you'd like to your bag. For instance, a hiker could lash a sleeping roll to their bag using the lash tab. Originally, it was added to bags to carry tools like axes."
https://www.amazon.com/Panef-Corp-Powdered-Graphite-Lubricant/dp/B0016GZQ60
Now I don't use hairpins but I would think the side WITHOUT the sharp pointed end would be better against your scalp?