North Mountain Supply #6.5 Solid Rubber Stopper – 3 Pack. These solid, non-drilled stoppers are made from food-grade, BPA-free rubber and are perfect for sealing carboys and fermentation vessels. Each stopper measures top: 1 3/8" and bottom: 1 1/8" (1 5/16" x 1"), creating an airtight seal to support proper fermentation. With a maximum temperature resistance of 70°C (158°F), this 3-pack is ideal for home brewing and fermentation needs. To promote a positive and satisfying customer experience, this product is covered by North Mountain Supply's 30 day hassle-free replacement program, in the event the product is damaged or defective.