In creating a sleeve for Thinkbaby bottles, Thinkbaby looked carefully at the solutions on the market. They wanted a material that would provide maximum insulation and protection, but also wanted to see how eco-friendly they could make the sleeve.
Thinkbaby's investigation took them to Patagonia. Patagonia largely pioneered the use of Limestone based neoprene to replace traditional neoprene for their wetsuits.
Thinkbaby's sleeves are made from Limestone. They feel just like traditional neoprene. They will not only protect the bottles, but will provide significant insulation.
Please note that these are made to fit tight, so they cannot be easily removed by a toddler.