PTFE is a highly resilient O ring material unaffected by virtually all known acids, alkalis and solvents. It is tough, abrasion resistant and capable of withstanding temperatures between -200°C to +250°C. It also possesses outstanding weather, ozone and electrical resistance. For this reason, it is the O-ring of choice for use in aerospace, food, pharmaceuticals and telecommunications industries. PTFE O rings could be a more economical alternative to FFKM materials, but they are not easily compressed and have little memory to be able to return to their original form. This can be a disadvantage if under permanent strain and may not create the best lasting seal.