Parah 12:8-9

Parah 12:8

If the outside of a flask containing sanctification water was rendered unclean, its inside is also rendered unclean and it conveys impurity to another flask, and that flask to another, even if there are 100 of them. A bell and clapper are considered connected for purposes of ritual purity. A spindle used for spinning reeds should not be sprinkled on its stick or ball (but rather on its iron stem) but if one did so, the sprinkling is valid. When it comes to a spindle used for spinning flax, the stick and the ball are considered connected. The leather of a crib fastened to its knobs is considered connected. Bed slats are not considered connected, neither to render impure nor to purify. All utensil handles that are drilled are considered connected. Rabbi Yochanan ben Nuri says the same is true of those that are jammed into the utensils.

Parah 12:9

The baskets of a saddle, a threshing bed, the corner of a bier, the drinking horns of travelers, a key chain, the loose stitches of laundrymen, and a garment sewn together with shaatnez (a prohibited mixture of wool and linen) are all considered connected when it comes to rendering impure but not for the purpose of sprinkling to purify.