LP341 filters are similar to LP340 antireflection-coated protective windows except that they have the added advantage of an oleophobic coating on one side. They are offered in 1mm or 2mmm thickness. The oleophobic (anti-smudge) coating repels fingerprints, oils and moisture build-up, allowing for far easier cleaning. Frequent, uncontrolled rubbing during attempts to clean deposits or debris from the front surface of a lens will often cause scratching or pitting that results in loss of transmission and image clarity.