This "tool" is nothing more than a very thin and soft plastic thread, which can be used to determine the operating clearance of plain bearings in a few seconds
Available in three size ranges:
PL-X 0.018 -0.045 mm: mainly for motorcycles
PL-A 0.025 -0.175 mm: for general use
PL-B 0.1-0.25 mm: for general use