... both high temperature and low temperature outside. frost resisting black slates , black cuture stones, black cultural stones No radioactivity, ... genuine healthy black slates, black cultural slates / black cultural slates .Stone Form: Black slates, cut-to-size slate, slate ... ")61.0x61.0x2.0cm (24"x24"x3/4")Other sizes as per customers' requirement.Thickness:1cm, 1.2cm, 1.5cm ...