Profile: S T D Specialty Filters, Inc. manufactures synthetic filters. Our product line includes pleated felt filters, felt gaskets, felt untreated and metal cylinders. Our filters are used in air intake filters for small gasoline engines, freon gas filters, air filters, breather and ink & blue print copier. We deal with sewing plants that fabricate filter bages, cloths, pads, paper and media. Our mark II cartridges are used for gases, varnishes, chemicals and solvents.