As you found, the old L/XL is now just “XL.”
It’s confusing because a lot of folks used to refer to the old sizes by just the “first” size, i.e., S/M = Small, M/L = Medium, L/XL = Large, because... that seems to make sense, and “Small, Medium, Large,” seems like a pretty logical sizing system.
Especially early on when the sizing convention was changed, we used to have a lot of confused customers swearing they wore a “Medium” helmet (M/L), but they ordered a Medium, and it was too small (because it was an S/M), and I spent many hours having to explain the sizing—which is still the same sizing, at least in terms of the dimensions of the helmet shell, just the names were changed.
If you’ve been using a L/XL Bump (probably was called the Base Jump back then), then you want an XL FAST SF.
~Augee