Photons to Photos noticed that the macro extension tube PDF went missing from Fujifilm’s website so they made their own and filled in some additional details about Fujifilm’s extension tubes. They posted the X mount MCEX-11 and MCEX-16 here and the G mount MCEX-18G and MCEX-45G here. You can also see them above.
Update: Carsten sent in links to where Fujifilm moved them too so you can compare it with Photons to Photos chart. The X mount MCEX-11 and MCEX-16 here and the G mount MCEX-18G and MCEX-45G here.
Fujinon MCEX-11: B&H Photo / Amazon / Adorama
Fujinon MCEX-16: B&H Photo / Amazon / Adorama
Fujinon MCEX-18G: B&H Photo / Amazon / Adorama
Fujinon MCEX-45G: B&H Photo / Amazon / Adorama