The Iron Mesh is crafted out of four Iron Bars put in a square.
Right-clicking the Heavy Sieve with a mesh will insert it. It can be retrieved by shift-right-clicking the block with an empty hand. The Auto Sieve has a slot for the mesh right beneath the input slot. Meshes can also be inserted through automated means.
In Ex Nihilo Omnia, the Iron Mesh is able to sift through 256 blocks before it breaks. It can also be used inside Omnia's native Sieve blocks.
This item is disabled for Ex Nihilo Adscensio, as the mod adds an Iron Stiffened Mesh itself.