Fully Technora Constructed Enhanced Durability and Performance Retains Original Functionality and Grip Our top-selling friction hitch and autoblock has been revamped with stronger aramid fiber. The 6.8 mm HollowBlock2 is crafted from 100% Technora fiber, enhancing its abrasion resistance and durability. Its gripping power stems from the distinctive hollow-braid design, suitable for use as a prusik or Klemheist knot on ropes 7 mm or larger.