My 5 month old son has been wearing this particular necklace for a little over a month.. While I can say it is very good quality, I cannot speak to it's effectiveness as I haven't noticed a difference in his slobbering or fussiness.. My son still wants to chew on EVERYTHING, slobbers all the time, and I've noticed him sucking in his bottom lip lately, which tells me he's definitely experiencing teething discomfort. (Baby #3) I wasn't expecting a miracle product, but I was expecting it to be "wonderful" like everyone told me it would be...A little disappointed.