Washers are generally round plates with a hole, designed to distribute the load on a threaded fastener. They can also be used as spacers or to reduce vibration.
Polyetheretherketone (PEEK) is a superpolymer, or high performance thermoplastic which has excellent chemical resistance and is rated for continuous service to 464 degrees Fahrenheit. It has the best fire safety rating of all thermoplastics. It can be radiation sterilized, tolerating radiation to 1100 M rads without undergoing significant change. The Peek used in these fasteners has been reinforced with 30% glass fibers which improves tensile strength to 22,600 psi (pounds per square inch.). Peek resists water absorption, absorbing 0.11% when exposed to water for 24 hours. Peek is extremely impact resistant, rated at 13.6 foot pounds (on the Izod Impact Scale), which compares favorably against Nylon 6/6 at 3 foot pounds. Peek is below average in terms of dielectric strength, for a plastic, with a rating of 175 volts/millimeter (compared to Nylon with a rating of 550 volts/millimeter).