PEEK (polyetheretherketone) Shrink Tubing is considered the highest performing thermoplastic material doe to its ability to withstand extreme temperatures to 250°C, high pressure, and chemical fluids.  PEEK shrink tubing provides a "shrink to fit" layer of protection for critical components and wiring used in ultrahigh vacuum applications to 1 x 10^-10 Torr.

 

  FEP (flourinated ethylene propylene) Shrink Tubing offers a great dielectric strength at a much lower cost than PEEK but is limited to a lower temperature and vacuum range of 200°C and 1 x 10^-8 Torr.