Polyoxymethylene (POM) filament is also known as Acetal or Polyacetal. The company DuPont uses the trade name Delrin for Acetal Resin. It is a commonly used thermoplastic to engineer specific parts. Acetal filament has high stiffness, low friction, and excellent wear resistance. It has good elastic resilience and great dimensional stability. The filament has good chemical and heat resistance. Because of it's low friction, POM is routinely used as gear wheels, ball bearings, etc. It has high impact resistance, which is one of the reasons the M16 rifle's stock is made out of POM.