ue” air filters for BMW were specially made for us by Green, a European manufacturer with motor sport experience and excellent production methods. The filters are made to a very high standard to ensure the best airflow and cleaning properties.
They enjoy better air flow than many similar filter types, and the low pressure manufacturing process ensures that there is very little spillage of the black plastic into the woven cotton sheets (more spillage = less filtering area)

The facts:

• Deep pleats in the double-layered cotton create a 10-20% increase in filtration surface. This increase allows a greater volume of air to move more freely into your engine cylinders.
• Blue uses 2 layers of woven cotton compared to most other brands who use 4 layers of cotton gauze. There are 3 main benefits to woven cotton: it’s thinner, holds oil better, and is stronger.
• Blue filter’s rubber mouldings are almost exact around the edges with no wasted surface area. Using this more efficient
  process the air flow is greater than the same size filter that is injection moulded.
• Blue Longlife Performance Filters are designed to be oiled. The oil creates a positive (+) magnetic charge with the mesh, which
  attracts the negatively (-) charged dust particles. The dust and dirt builds around the mesh to form a tunnel. This allows the
  cotton to remain cleaner for maximum flow.
• Normal servicing every 50 000 km or once a year. In very dusty conditions re-oiling or servicing may be needed.
• Pleat design: The filters have pleats that are parallel to the width. This makes the filter more rigid and stronger and reduces
  air leaks.
• Stainless steel mesh on both sides.
• Custom Fitment Tabs (for square filters only). Plastic air-boxes can warp out of shape or even distort from the heat radiated
  from the engine. These tabs also benefit the filter by centring and aligning it in the air box, so the filter is evenly sealed.
• Easy to fit, just replace the original with Blue Filter.
• Warning sticker for air box.

These merits are not found on any regular paper type filter.
Despite the long period between servicing the clever multi-layer design ensures excellent filtering properties.