וְעָשִׂ֤יתָ לּוֹ֙ מִכְבָּ֔ר מַעֲשֵׂ֖ה רֶ֣שֶׁת נְחֹ֑שֶׁת וְעָשִׂ֣יתָ עַל־הָרֶ֗שֶׁת אַרְבַּע֙ טַבְּעֹ֣ת נְחֹ֔שֶׁת עַ֖ל אַרְבַּ֥ע קְצוֹתָֽיו׃
And thou shalt make for it a grating of network of brass; and upon the net shalt thou make four brazen rings in the four corners thereof.
Read kabbalistic (mystical) interpretation of Exodus 27:4: and classical mystical sources.