The WonderPana 66 System from Fotodiox is a kit that combines the Core Unit with the Upgrade Bracket. This allows you to attach different filters to the Canon 17mm TS-E f/4L lens. The Core Unit accepts all 145mm filters including UV, circular polarizer and neutral density filters. When the Upgrade Brackets are attached, the system holds the 66 filters, which are 6.6 x 8.5" rectangular filters. The core unit also doubles as a metal hood, protecting the front element of your lens. A snap-on lens cap is included and fits onto the metal core unit.