PEEK is a colorless organic thermoplastic polymer in the Polyaryletherketone. PEEK is a semicrystalline thermoplastic with excellent mechanical and chemical resistance properties that are retained at high temperatures. Some grades have an operating temperature of up to 250⁰C. It is highly resistant to thermal degradation, and resistant to attack by both organic and aqueous environments. It has high resistance to biodegradation. PEEK is used to fabricate items demanding applications. PEEK is used in medical implants, for example in creating a partial replacements skull in neurosurgical applications. PEEK offers a combination of superlative properties that allow PEEK to effectively replace metal in some of the most severe end-use environments.