Keilim 25:2

An ox goad (which has a hoe at one end and a prod at the other) has different rules for its outside and its inside – from seven handbreadths (about 21”) to the hoe and from four handbreadths (about 12”) to the prod; this is the opinion of Rabbi Yehuda. Rabbi Meir says that an ox goad doesn’t have different rules for its outside and its inside; the measurements of seven handbreadths and four handbreadths were only mentioned regarding a goad’s broken pieces.

Keilim 25:3

Measures for wine or oil, a soup ladle, a mustard strainer and a wine filter all have different rules for their outsides and their insides; this is the opinion of Rabbi Meir. Rabbi Yehuda says that these utensils don’t have different rules. Rabbi Shimon says that they do have different rules; if they’re rendered impure on the outside, their contents remain pure but the utensil must be immersed.