Do i need a cylinder refill agreement yes if you dont have an empty 45kg butane or 39kg propane bottle you will need to purchase a new 45kg butane bottle along with a cylinder refill agreement of 3999 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 45kg butane bottle upon delivery what is a cylinder refill agreement when you firs