Sororities Category • Double wall insulated to keep drinks cold for up to 8 hours and also keeps drinks hot for up to several hours • Matching slider lid is provided for drinking on the go (except for 16oz Short Tumbler) • BPA free and California Prop 65/FDA tested • Base and walls of the tumblers are thicker than competing brands making them ~15% heavier and feel more like glass than plastic • Insulate longer by approximately 5% due to thicker walls and base