2x CO2 cartridges and valve, inner tube, multi tool, spoke key (specific size), quicklink and a £2 coin.
All in a small Lezyne micro caddy which doesn’t rattle or move. Winter and summer bike both have the same so I don’t have to worry about swapping it over or forgetting. It’s barely noticeable under the saddle and leaves pockets free for important stuff like food, rain jacket, warmers, phone etc.
The 29er has the same apart from being in a medium-sized micro caddy due to the increased inner tube size.