Fotodiox Pro 6.6x8.5-" filters are the strongest in the industry at 4mm thick. Fotodiox 6.6x8.5-" filters are practically unbreakable and are assured spectrally neutral to within or and ldquo; 3 in the a and b channels of the lab Color: space. Fotodiox Pro filters are also assured to be within or and ldquo; 2 in regards to total light transmission. Fotodiox currently offers 6.6x8.5 in 4 Graduated Neutral Density ND filters:.6 Soft Edge.6 Hard Edge.9 Soft Edge and.9 Hard Edge. This filter is made by Fotodiox Pro specifically for the WonderPana 66 Systems. FeaturesPremium Grade Optical Glass FilterHigh Quality Super Thick Multi-Coated Graduated ND4 FilterPremium Grade FilterOther 6.6x8.5-" Filters Include:.6 SE.6 HE.9 SE.9 HE24 Month WarrantyIncludes:6.6x8.5-" Grad ND.6 Soft Edge Filter with Carrying PouchSpecificationsSize: 6.6 x 8.5 in. Handle: 6X8-Nd-0-6SeDimensions: 168mm x 203mm x 4mmConstrustion: Premium Grade Anodized Aluminum Optic Grade Organic GlassWarranty: 24 MonthsWeight: 454 g