Fine meshes are most often specified by "mesh count". Mesh count is the number of wires per inch and is usually the same vertically and horizontally. Rectangular weave is also available as special order.
"Market Grade" is the industry standard wire diameter for a given mesh count, and is the most commonly available. Other wire diameters may also be available from stock, or can be manufactured.
The common alloy is T304 stainless steel, but T316 is readily obtainable. Other alloys and materials can also be supplied. Please contact Screen Services with your particular requirements.
Fabrication services such as cutting to size, slitting, circle cutting, forming, and welding can also be provided by Screen Services.