מסכת כלים

פרק כט משנה ב

The following mishnah lists how many of various types of item can be attached to each other and be considered חבור לטמאה, attached for the purposes of tumah wherein if one becomes tamei, those attached to it become tamei.  Also addressed if חבור להזיה, where if items are attached to each other and become tamei from a corpse, sprinkling the purification waters on one will render the other tahor as well.

שלש כסתות של צמר

Three mattress of wool,

six of linen,

three sheets,

twelve matpechos (small pieces of cloth, often used as hand towels or kerchiefs),

two trousers,

one shirt,

one cloak,

one winter cloak (i.e. these three items cannot be attached to a second item),

are (considered) attached for tumah

and sprinkling;

more than that

are attached for tumah (as a rabbinically imposed stringincy)

and are not attached for sprinkling;

Rabbi Yosi says

also not for tumah.

חוט המשקלת

A plumb line (this was a sting from which a metal weight was suspended, and it was used to ensure that a wall or other item was plumb, or perfectly vertical),

(to be considered attached to the metal weight for the purposes of tumah and taharah could be a maximum of) twelve (handbreadths),

that of carpenter,

eighteen,

that of builders,

fifty amos;

more than that

(even) if he want it to keep it (at a length exceeding these measures)

it is tahor (and not considered attached);

that of plasterers

and that of muralists (both of whom do their work on walls)

any amount (there is not maximum for these).