STAY CHILLED ORIGINAL BOTTLE COVERS ARE MADE FROM NEOPRENE (EXACTLY SAME MATERIAL USED FOR DIVING WETSUITS). ACTING AS AN INSULATOR IT KEEPS YOUR DRINK COOLER FOR LONGER. THE COLDER THE BOTTLE CONTENTS, THE BETTER RESULTS YOU WILL GET !! ALSO COMES WITH ADHESIVE NUMBERS SO YOU CAN PERSONALISE YOUR COVER WITH YOURS OR YOUR FAVOURITE PLAYERS NAME AND NUMBER