My DS5 received a set of these for his birthday. As his little brother - age 3 - likes to put things in his mouth we have been very careful to keep these out of his reach. We only let DS5 play with them when we are supervising and they are kept in a special box. Well I don't know where my mind was a couple of weeks ago but - DH ran out to buy pull-ups (it was late 9:30 pm-ish) and I was getting the boys ready for bed and the little one asked me if he could "play with brother's toys?" Well since they had played together with them so nicely earlier, I got the box down and let him sit on the floor with them. As I turned my back to put something in the kitchen I heard a deep breath, a cough, then a gasp! You guessed it, he SWALLOWED one of the metal balls. I freak out! Made sure he was breathing, called my DH to "GET HOME NOW" and headed to the local ER. Well after some xrays and a not so sure Physician's assistant, they declared that he may or may not have swallowed it and we would have to "check to see if it COMES OUT" if you know what I mean! Lesson learned! I will NEVER turn my back on this child EVER again! We call him our ER boy - sprained an ankle at age 1 throwing a temper tantrum, spent New Years Day at the ER in Florida at age 1 & 1/2 instead of at Animal Kingdom - fell at the rental house and smacked the center of his forehead on the metal corner of a glass table, at age 2 split his chin open on a bike helmet while pushing a ride on toy, now this at age 3! This child is the epitamy of "a typical boy!" Just thought I would prevent someone else from having as much gray hair as me!! As a side note, my DS5 LOVES THESE!