Zoe has worn one since she was 18 months old. I have tried several different companies...I like the plates from Petitebaubles.com , they do great engraving also. Word of advise is to get real crystals, anything with like a painted color on it tends to wear off. Also get real silver beads and clasps. Zoe never takes hers off, she swims, bathes, etc... with it on.
I put Zoe's name, Cystic Fibrosis, and Meds on Back on the front.
Then I list her meds, NKA, ICE phone number, and blood type on the back.
Take care,