This B&W 77mm 486 Digital UV/IR Blocking Filter has a completely colorless glass carrier coated with a number of extremely thin, partially reflecting layers with precisely computed thicknesses, similar to MC coating (multi-coating).
The B&W 486 Filter is not an "absorption" filter. It interferes with unwanted UV and IR radiation which affects the wavelengths of both ends of the visible spectrum. The disruption occurs when these two variables scatter between each other and cause a drop-off effect.
The filter ring is made from brass yielding a stronger product. Brass filter rings are also less prone to jamming. In addition, the seal between the glass and filter ring is exceptionally strong giving the filter added strength and durability.
In production, the filter glass is dropped into the empty filter ring from the rear and held in place with a threaded retaining ring; this is a definite advantage over a competitor who uses a spring clip to hold the glass in place. A threaded retaining ring will hold the glass firmly and securely in place to avoid the possibility of rattling and provide perfect parallelity and flatness to your front lens element for ideal optics. The part about additional filters not binding is due to the fact that brass is a very stable metal and does not contract or expand like alloy.
The reputation of B+W's Schott glass is world renowned. The high production standards combined with a sturdy brass filter ring make B+W filters hard to beat. These filters have a "heft" to them that is impressive. They may feel heavier but the benefit is in the construction and results. Not only is the glass exceptional but so is the seal between the ring and glass. Schott Glass used in the manufacture of this filter is legendary and synonymous with the highest standards of filter production. It comes with a solid 10-year warranty.