Knitted wire mesh is a metal wire or plastic strand knitted into a mesh structure in very much the same way as stockings or sweaters. It is in no way related to the woven metal materials familiar to us as fly screens.
 

Knitting produces mesh of interlocking loops. These loops can move relative to each other in the same plane without distorting the mesh, giving knitted mesh a two-way stretch. This cannot be done with woven meshes, as there is always some form of connection between the wires at the corners of the square openings.

From a functional point of view, it is this flexibility that gives knitted mesh its unique advantages for industrial uses.