Many pre-made microwavable products use metal to direct&#x2F;control heating. The most well-known is probably &quot;hot pockets&quot;, which use a metal-lined sleeve known as a &quot;susceptor&quot;.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Susceptor" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Susceptor</a>