Bests & Worsts Reviews from Amazon

I purchased two of these bags, for my 5 and 7 year old. We took one trip to San Francisco and the bags were great--the kids used them through the terminal and everyone who passed by us asked where they could get one. I even had a flight crew come up to me and tell me how cute the kids were on their scooter bags and they wanted the adult version. The scooting system was smooth and the steering was really easy...even for my 5 year old. The compartment for the luggage is small but just the right size for the kids to carry their own stuff (a week's worth of clothes). Unfortunately, the first time I unzipped the bag the plastic that holds the top and bottom together (see pictures) broke--on BOTH of the bags. I'm trying to figure out if I should get a refund or exchange the bag (because my kids did love the bags so much). Is this a fluke or your standard quality after one use?!?