How often should I replace the hygiene kit, and how do I do it?

The hygiene kit should be changed at least twice a year. To replace it: remove the old sound absorber foam and insert the new one, pull off the old ear cushion and press the new one into place around the edges, then pull off the old head cushion and insert the new one. Make sure to choose the correct hygiene kit (part number 99403-001) for your hearing protector. (Pages 5, 7)