Profile: Koch Filter Corp. manufactures huge variety of commercial and industrial filters. Our product line includes hospital air filters, industrial painting & coating filtration, gas turbine air intakes, automotive plant filters, and office buildings air filters. Multi-Pleat GT filters are specifically designed for use as a prefilter in gas turbine applications to help extend the life of more expensive final filters. Durable and efficient, the Multi-Pleat GT is an ideal choice for many gas turbine applications.