Yes it is polyprop, costs just pennies to play around perfecting technique. As I stated, they aren't meant to be used and will never be found on my boat.
As far as I can tell, the spacing between the marks is there to determine loop size which I have done simply by forming the loop and then marking it. I wonder though, given the price of everything else we do to our boats, is an extra dollar of line going to be that detrimental?
BTW, my "fid's" bear a striking reseblance to phillips head screwdrivers.