Using NBTTagCompound

[Asyc]

Hello modding community, I am working on an API mod and I have a class called GasContainer that extends Item(which will be extended to create gas containers) then I have 2 more classes, one called Gas, and the other Atmosphere. In the Gas class I have a double called amountInAtmosphere, and I need help storing that int value without creating a nbt tag compound in onRightClick, I need to know where to load the nbt key right when the player loads into the game. Any suggestions?

[Asyc]

Alright, Thanks!