My husband purchased this necklace for our 4 month old, who recently has been showing all the signs of teething. We have a very happy, content, smiley baby - but recently she has not been that way. We figured it was part of the 4 month learning stages, sleep regression, etc (we have 2 older kids who we never used these necklaces with). this is day number 3 of wearing the necklace and she is back to her normal self! she has been sleeping, happy, the drooling has almost stopped, and she is visibly more comfortable now. Maybe a coincidence, but I think this product is working and working well! I wish I would have known about these years ago with my other kids.