Our Neoprene Carboy Sleeve works great for maintaining the internal temperature of your 5, 6, or 6.5 gallon glass carboy. Highly recommended for use with the Carboy CoolStix™. The added insulation will lower the amount of cycles needed to maintain fermentation temperatures and greatly assist in cold crashing. The sleeves are 6 mm thick with stitched piping on the edges for exceptional durability.