No seriously, it helps to fix the slow retract issue. I should have taken pics, but failed. Here are the steps though:
  1. Pull seat belt all the way out
  2. Use a clamp to prevent it from retracting
  3. 5 gallon bucket with hot soapy (I used dish soap) water
  4. Put as much as you can into the bucket
  5. Use a rag and wipe up and down the entire length of the belt
  6. Be grossed out by how dirty the water is
  7. Allow the belts to dry completely before pulling the clamp off and letting them retract
  8. BAM! Enjoy belts that retract again