Mishnah Kelim 19:10-20:1

A dung-basket that was so damaged that it will not hold pomegranates: Rabbi Meir says is still susceptible to uncleanness, But the sages say that it is clean because if the primary function ceases the secondary one also ceases.

Pillows, bed coverings, sacks and packing cases that were damaged are still susceptible to midras uncleanness. A fodder-bag that can hold four kav, a shepherd's bag that can hold five kav, a traveling bag that can hold a se'ah, a skin that can hold seven kav, Rabbi Judah adds: also a spice-bag, and a food wallet that can hold the smallest quantity are susceptible to midras uncleanness. If any of them was damaged it becomes clean, since if the primary function ceases the secondary function also ceases.