The ox tether is used for stone and iron delivery. It houses an ox, which automatically seeks out a quarry or iron mine without the need of a handler.
An ox can collect a maximum of 16 stone blocks/8 iron bars, yielding 32 stone/8 iron with a full load.
By default, the ox automatically visits the nearest iron mine or stone quarry for materials, gets them loaded and then brings them to the stockpile. This can be overridden by a rally point, which makes the ox visit the nearest mining facility instead.