he Etymotic Tuning Kit was derived from the desire for Etymotic users to modify the sound of their earphones. To each of us, the sound we hear from any hearing device sounds different as we all have different frequencies curves to our natural hearing based on age, ear shape, previous hearing damage, etc. What Etymotic is offering is the listener the ability to tune their Etymotic ER series earphones to their own tastes and hearing profile. By incorporating five different filters of varying resistance you can go from a more detailed sound using the white filters all the way to a warmer and darker sound if you go with the orange filters. Kit includes four filters of each color.