There is no minimum size [for a hole] that is made for a stick, a ‘‘sword,’’ or a lamp, according to Beis Shammai. Beis Hillel say: A square handbreadth. [If a hole was made] to be a peephole, to speak with his friend, or for other usage, the minimum size is a square handbreadth.

The following items reduce the [opening to less than a] handbreadth: Less than an olive-sized piece of flesh reduces [the opening if the source of tumah] is a quarter [of a kav] of bone; a piece of bone smaller than a barleycorn reduces [the opening if the source of tumah] is an olive-sized piece of corpse flesh; less than an olive-sized piece of corpse flesh; less than an olive-sized piece of carcass; less than a lentil-sized piece of sheretz; less than an egg-sized piece of food; grain [covering] the window; a thick spider web; the carcass of a kosher species of bird that was not designated [for food]; the carcass of a nonkosher species of bird that was designated [for food] but was not rendered capable of contracting tumah, or it was rendered capable of contracting tumah but was not designated [for food].

The following items do not reduce [the opening to less than a handbreadth]: Bone does not reduce if [the source of tumah is] bone; flesh does not [reduce] if [the source of tumah is] flesh; an olive-sized piece of corpse flesh does not [reduce the opening]; an olive-sized piece of carcass does not; a lentil-sized piece of sheretz does not; an eggsized piece of food does not; grain [growing] in the window does not; a very thin spiderweb does not; the carcass of a kosher species of bird that was designated [for food] does not; the carcass of a nonkosher species of bird that was designated [for food] and was ren-dered capable of contracting tumah does not; warp and woof threads that have con-tracted tzaraas do not. Also a brick made from a beis hapras does not; these are the words of R’ Meir. The Sages say: The brick reduces [the opening], because its earth is tahor. This is the rule: Anything that is tahor reduces [the opening], and anything that is tamei does not reduce [the opening].

A ziz-type ledge conveys tumah even if its width is minimal; whereas gizrah- and gavlis-type ledges [convey tumah] only if they are a handbreadth wide. What is a ziz-type ledge? [A ledge] whose face extends downward. And [what is] a gizrah-type ledge? One whose face extends upward. When does a ziz-type ledge convey tumah even if its width is minimal? When the ledge is three rows of stones, which is twelve handbreadths, above the doorway. [If the ledge] is higher, it spreads tumah only if it is a handbreadth wide. Ornamental archways and awnings spread tumah if they are a handbreadth wide.