Reference for Kelim 27:5
בְּלוֹיֵי נָפָה וּכְבָרָה שֶׁהִתְקִינָן לִישִׁיבָה, רַבִּי עֲקִיבָא מְטַמֵּא, וַחֲכָמִים מְטַהֲרִין עַד שֶׁיְּקַצֵּעַ. כִּסֵּא שֶׁל קָטָן שֶׁיֶּשׁ לוֹ רַגְלַיִם, אַף עַל פִּי שֶׁאֵין בּוֹ גָבֹהַּ טֶפַח, טָמֵא. חָלוּק שֶׁל קָטָן, רַבִּי אֱלִיעֶזֶר אוֹמֵר, כָּל שֶׁהוּא. וַחֲכָמִים אוֹמְרִים, עַד שֶׁיִּהְיֶה בוֹ כַשִּׁעוּר, וְנִמְדָּד כָּפוּל:
Regarding worn-out pieces of a sifter or a sieve that one adapted for use as a seat, Rabbi Akiva consideres them [susceptible to being rendered] impure, and the Sages consider them pure until one trims them [for use as a seat]. A child's chair which has legs, even if it is less than a handbreadth high, is [susceptible to being rendered] impure. Regarding a child's robe, Rabbi Eliezer says: [it is susceptible to impurity] at any size; and the Sages say: only once it is of the prescribed measure; and it is measured doubled [i.e. folded] over [such that it must actually be twice the required measure].