Polarising Filters stop reflections and glare from water, glass, foliage, blue skies and metallic surfaces. By rotating the front of there CPL filter, the area of reflection or glare can be targeted and removed allowing more colour and details in objects or surfaces that emit gale. Circular Polarising Filters act the same way your polarised sunglasses do, and just like your sunnies, these filters are most effective in bright day light. Read more about them here.
Aluminium is lighter and more malleable which can be susceptible to bending or distortion with heavy use. This means you increase the risk of damaging the lens threads over time. Brass is much harder and more accurate giving you peace of mind that your lenses are safe. Titanium adds another level of protection as the metal is less likely to shrink and expand in varying weather, this is perfect for those adventuring in harsh conditions!