NWT - Black Silicone Boot for Stanley Tumblers Fits the Stanley 40 oz Adventure Quencher Tumbler, Stanley 30 oz 20 oz IceFlow tumbler. A flexible compatible hydro sport water bottles and regular water bottles of 12/16/18/20/21/24 Fluid Ounces with bottom width 2.83"-3". Durable bottom boot helps protect against dents, dings and damage, extra protection to your water bottles bottom, Non-Slip, No noise. BPA free, non-leaching and non-toxic, no hazardous chemicals.