Keilim 26:5

The following hides are susceptible to midras impurity: one intended for use as a rug, one used as an apron, as a bed spread, by a donkey-driver, by a flax worker, by a porter, by a doctor, for a crib, for a child’s bib, for a cushion. for a mattress. All these are susceptible to midras impurity. Rabbi Eliezer says that a hide for combed wool and one worn by a wool comber are susceptible to midras but the Sages say they are only susceptible to corpse impurity.

Keilim 26:6

A cover or wrapper for clothes is susceptible to midras impurity. Beis Shammai say that a cover or wrapper for purple wool is susceptible to midras impurity but Beis Hillel say they're only susceptible to corpse impurity. A hide that was made into a cover for a utensil is insusceptible to ritual impurity but one for weights is susceptible; Rabbi Yosi says in the name of his father that it is insusceptible.