Midwest Optical Systems AC900-40.5 Acrylic Short-Wave Infrared Longpass M40.5 Acrylic Filters Acrylic Longpass Filters are a durable, lightweight and economical solution for inspection windows. They can protect a lens in environments where broken glass might pose a problem.Acrylic Longpass Filters are frequently used for lens protection and economical enclosure windows, as well as over light sources to control the wavelength emission of broad spectrum light sources. Because of their durability, they’re commonly used in Food & Drug Administration (FDA) and European Food Safety Authority (EFSA) regulated applications where glass over the inspection area is not permitted. AC370 and AC380 offer anti-abrasion, anti-reflection coating, which can also withstand harsh solvents such as alcohol, acetone or MEK.