Commentary for Kelim 19:3

המיזרן (girth, hanging from the bed – a strap of cloth which is wound over the bed to keep the covering in position) – a kind of girdle or woven belt that they tie around the bed in order to attach its joints/links. But sometimes it is too large and it drags and extends beyond the bed.

If a part of a mattress hangs over, it is unclean whatever its length, the words of Rabbi Meir. Rabbi Yose says: only that which is shorter than ten handbreadths. It seems that during the time of the Mishnah, not all beds were used with mattresses. The Geonim (rabbis in Babylonia in the 8-11th centuries) defined the word that I have translated as "mattress" in the following way: "a wool garment which rich people put on their beds underneath the regular bedding. And they put it on the edge of the bed frame." If the mattress hangs over the bed, according to Rabbi Meir no matter how long the part that hangs over is, it is all considered to be connected to the bed and if the bed is impure, all of the mattress is impure. Rabbi Yose says that only that which is shorter than ten handbreadths (this is quite long). Anything longer is already far enough away from the bed that it has an independent status of impurity.

היוצא מן המטה – and the bed is impure from treading.

The remnant of a mattress remains unclean if the length is at least seven handbreadths from which a donkey's covering can be made. The remnant of a mattress can remain unclean if it is at least seven handbreadths long, because this is the measure that could be used to make a donkey's covering. This goes according to the general principle that as long as something can still be used as a vessel it retains its impurity.

כל שהוא – even if it extends outward a few cubits beyond the bed, everything is impure.

ר' יוסי אומר עד עשרה טפחים – it is impure through the defilement of the bed. From ten [handbreadths] and beyond it is pure. And the Halakha is according to Rabbi Yossi.

שיירי מיזרן – a girth that was worn out or torn, whatever that will remain from it, and it will be ritually impure.

שבעה טפחים – for less than this, it is not appropriate for anything and it is not considered a vessel.

חבק (a band with which the saddle or housing of an animal is fastened around its belly) – there are those who explain/interpret , a thick and hard piece of cloth that they place on the donkey when it comes from the road and it is sweating, , in order that it not catch cold when they remove the saddle from it. And there are those who explain, that they place it on the burden of the donkey in order that it not be lost if rains fell upon it.