Keilim 17:8

The olive mentioned in halacha as a measure is neither large nor small, but medium-sized, i.e., the Egori olive. The barleycorn mentioned in halacha as a measure is neither large nor small, but medium-sized, i.e., the desert barleycorn. The lentil mentioned in halacha as a measure is neither large nor small, but medium-sized, i.e., the Egyptian lentil. All movable objects convey ritual impurity if they are the diameter of an ox goad (mishna 9:7) – the referent is neither large nor small, but a medium-sized ox goad. A medium-sized ox goad is one whose circumference is a handbreadth.

Keilim 17:9

The cubit mentioned in halacha as a measure is neither large nor small, but medium-sized. There were two cubit measuring rods kept in Shushan HaBirah (the name of a room on the Temple Mount), one in the northeastern corner and one in the southeastern corner. The one in the northeastern corner exceeded the cubit of Moshe by a half-fingerbreadth, while the one in the southeastern corner exceeded the first one by another half-fingerbreadth, with the result that it exceeded the cubit of Moshe by a fingerbreadth. There was a larger cubit and a smaller cubit so that craftsmen would take orders according to the smaller cubit and deliver according to the larger cubit; this was to avoid the possibility of misappropriating Temple funds.