Fiberglass Cloth, 3.1 oz, 16.5 " wide. 3 Yard Roll. 4HS Crowfoot Weave, Style 120. Style 120 fiberglass cloth is a 4 harness satin weave with a thread count of 60 x 58 ends/inch, uses the yarn ECD 450 1/2 in the warp and fill. The D glass filament diameter is 5 microns where the similar fabric styles 220 and 2220 use the larger 7 micron E filament. Style 120 also uses two half weight yarn twisted together. The smaller filament and twist in the yarn makes a more pliable fabric. However, even with a more flexible fiberglass cloth by design, the finish on this particular weave can greatly affect it's flexibility.