If you do any paper piecing I think these are a must. You can clip sections together without the distortion that pins cause trying to pin thru 2 layers of paper and the layers of fabric. And since they're flat on the bottom they slide along while sewing without catching on the machine bed. They slide off easily as you sew towards them so you don't have to stop in order to remove them as the needle approaches. I got a pack of 50 on Amazon and they are worth every penny to me.