The NiSi Allure-Streak BLUE Filter for IP-A Filter Holder (2mm) is a special effects filter designed to render a single light ray from a point light source. This filter features a single series of etched lines spaced 2mm apart, which run across the filter surface. The filter creates the effect of elongated blue streaks horizontally from the light source usually seen when using an Anamorphic type of lens. The filter has a rotating front (similar to how a CPL rotates) and when the filter is rotated, the orientation of the light ray can be adjusted to suit your composition or desired effect. The NiSi Allure-Streak BLUE Filter for IP-A Filter Holder is compatible with the NiSi IP-A filter holder for iPhone (Sold Separately) and attaches using a patented quick bayonet mount. To install NiSi IP-A circular filters align the circular filter bayonet to three installation positions. Ensure that the outer bayonet of the filter aligns with the IP-A holder slot and turn clockwise to tighten. If multiple filters need to be installed, align the three bayonets on the second round filter with the three holes on the filter clip slot fixed on the IP-A holder. Ensure that the outer bayonets of the filter are completely aligned with the round filter clip slot, then turn clockwise to tighten.