This 40.5mm PD WMC UV Filter from Benro is primarily designed to eliminate ultraviolet light, avoiding a degradation of image contrast. This is particularly noticeable when photographing outdoor scenes, where a UV filter will work to combat the faded blue or white effect that ultravoilet light can cause. All filters will also offer a degree of protection for the front element of your lens against moisture, dust and scratching.
The WMC abbreviation is short for Waterproof Multi-Coating, which as well as being anti-reflective, makes this filter water and oil repellent and fingerprint and scratch resistant. It features a rugged aluminum alloy filter ring and high quality optical material.
Please note that the item pictured is 77mm, however this listing is for the 40.5mm PD WMC UV Filter.