Markforged 150cc High Temp Fiberglass CFF SpoolMarkforged 150cc high temperature fiberglass CFF spool High Strength High Temperature (HSHT) Fiberglass exhibits aluminum strength and high heat tolerance. Parts with inlaid continuous fiberglass are setting benchmarks in the market and, through a patent, only possible on Markforged systems. Five times as strong and seven times as stiff as Onyx, its best used for parts loaded in high operating temperatures.