Polyester and nylon slings are very similar but do have a few key differences. Polyester slings cannot by used in an environment that has Aldehydes or Ethers and will be negatively affected by concentrated Sulfuric Acid and strong Alkalis at high temperatures. Nylon slings cannot be used in environments with Acid or Bleaching Agents. The amount of stretch each material has also differs. Polyester stretches to about 3% at rated capacity, but nylon stretches to about 10%. Polyester and nylon are equal in strength.