The 40.5mm Streak 3mm Filter from Tiffen 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 3mm apart from each other, which run diametrically across the filter surface. This filter is set in a non-rotating mount and can be used in conjunction with a filter holder or other filter to adjust the orientation of the light ray to suit your composition or desired effect. It is constructed from clear optical-grade glass and mounted in an aluminum filter ring.