Hoop, 28" Diameter. This hoop carries no branding so I cannot say for sure if it is a Hula Hoop but that is what comes to mind when I look at it. The joint is taped; the hoop is relatively rigid so holds shape well. It sounds hollow with sand or something similar moving inside. The outward appearance shows sparkles. I listed it as outdoor but of course it could be used inside so long as sufficient space is available. The diameter measurement is approximate roughly center-center of the tubing across width.