Johns Manville Micro-Fiber® Felt is manufactured using Type 475 borosilicate glass fibers using a water deposition process that results in a lightweight, flexible, binderless felt with excellent handling qualities and superior thermal and acoustic performance. Micro-Fiber Felt is designed for the insulation of aircraft components and jet engine ducting and can be used as air and gas filtration media. It is available in a variety of densities and can withstand continuous exposure to hot face temperatures of up to 900°F (482°C).