ʻO nā metala perforated he mau ʻāpana kila, aluminika, kila ʻole a i ʻole nā mea hoʻohui kūikawā i kuʻi ʻia me nā puka poepoe, ʻāpana a i ʻole nā puka hoʻonani i kahi ʻano like. ). Ka nui o ka puka maʻamau mai .020 a i 1″ a ʻoi aku.