Reference for Kelim 25:1
כָּל הַכֵּלִים יֵשׁ לָהֶם אֲחוֹרַיִם וָתוֹךְ, כְּגוֹן הַכָּרִים וְהַכְּסָתוֹת וְהַשַּׂקִּין וְהַמַּרְצוּפִין, דִּבְרֵי רַבִּי יְהוּדָה. רַבִּי מֵאִיר אוֹמֵר, כֹּל שֶׁיֶּשׁ לוֹ תוֹבְרוֹת, יֶשׁ לוֹ אֲחוֹרַיִם וָתוֹךְ. וְכֹל שֶׁאֵין לוֹ תוֹבְרוֹת, אֵין לוֹ אֲחוֹרַיִם וָתוֹךְ. הַשֻּׁלְחָן וְהַדְּלֻפְקִי, יֵשׁ לָהֶם אֲחוֹרַיִם וָתוֹךְ, דִּבְרֵי רַבִּי יְהוּדָה. רַבִּי מֵאִיר אוֹמֵר, אֵין לָהֶם אֲחוֹרָיִם. וְכֵן טַבְלָא שֶׁאֵין לָהּ לִזְבֵּז:
All vessels have [a distinction, with regard to purity status, between their] outsides and insides, for instance: cushions, and blankets, and sacks, and packing-bags, according to Rabbi Yehuda. Rabbi Meir says: anything which has loops [through which to thread a drawstring] has [such a distinction, with regard to purity status, between its] outsides and insides; but any which does not have loops, does not have [such a distinction between its] outsides and insides. A table and a serving table have [such a distinction between their] outsides and insides, according to Rabbi Yehuda. Rabbi Meir says: they do not have outsides [i.e. they have no such distinction]. And similarly regarding a board that has no rim.