Do i need a cylinder refill agreement yes if you dont have an empty 5kg or 13kg patio propane 13kg propane 15kg butane or a 6kg bbq butane bottle you will need to purchase a new 15kg butane bottle along with a cylinder refill agreement of pound3999 which is automatically added to your basket no if you currently have an empty bottle of those listed above then all you need is a gas refill simply exchange your empty bottle for your new 15kg butane gas bottle upon delivery what