Helper Hut at Town Hall 9: max level 9. At Town Hall 18 the cap is level 11. It unlocks at Town Hall 9. Max level per Town Hall: TH9 9, TH10 10, TH11 11, TH12 11, TH13 11, TH14 11, TH15 11, TH16 11, TH17 11, TH18 11.
Tap a Town Hall to open this item there. Dashed: not available at that Town Hall yet.