Heliopan glass filters are made exclusively with glass from Schott (Zeiss) the world's finest optical glass supplier. Heliopan filters are "dyed in the mass" and ground, polished and coated to the highest standards of the German optical industry. All Heliopan screw-in type and series size filters are mounted in precision black anodized brass rings to eliminate binding or cross threading and to ensure optimal alignment. The care, quality and performance of Heliopan's filters make them simply the world's finest filters! Heliopan supplies screw-in filters in all sizes from 19 x 0.5 mm to 145 x 1 mm. They offer all series sizes from series IV to 138 mm. They make square filters in 2 x 2 to 4 x 4" sizes and rectangular filters up to 4 x 6" sizes. All Rollei and Hasselblad Bayonet sizes are available, as are Nikon drop-in 39 mm filters, Minox push-on filters and numerous other types. Besides the usual range of filters, Heliopan supplies 16 different types of polarizers, Zeiss Softars (always made of acrylic) , Graduated wide-angle filters, Digital and Video filters, and a full range of special effect filters. All filters that will benefit from coatings are hard coated on both sides, 16 layer multi coatings are also available on many Heliopan filters. Heliopan also offers a complete range of step-up rings for filters up to 105mm and lenses as small as 27 mm. Heliopan also supplies Hasselblad, Rollei and Zeiss bayonet to screw mount adapters and Hasselblad screw mount to bayonet adapters. Also, supplied are metal and rubber lenshoods from 24 to 122 mm and gel and glass filter holders for up to 4" glass filters. On special order, custom adapters are available.