Made of high Quality TPU Material which is made from Azo Free and Phthalate free chemicals. Set of 2 bottle holders include one carabiner and one keychain which can be swtiched between each other. Can be utilized to hang keys or during hiking it can be used as bottle holder with backpack. Inside diameter which will hold bottles is 2.5 cm and can support famous bottles like Aquafina, Nestle or Dasasni. Exterior Diameter is 3.8cm.