Originally Posted by
maviskw
If you make a "Stack 'n' Whack", you need to cut through fabric which has many pins in it to hold the pattern in order. The ruler is placed over the pins and the cut is made. Many cuts are made over the pins. Glass head pins don't work well here.
Nor would these magic pins be desirable for this procedure as they would leave it too lumpy.
You would need the long flat headed pins to cut through all the layers without distortion.