This optical, focusing spot can be used to project patterns or masked shapes onto your set. Accepts "M" size (2.6"/6.6cm) Rosco pattern disks. Projects a spot as small as 2" (5cm) diameter from a distance of 3' (91cm). Attaches to any Calumet Series 2 flash head (Traveller or Elite). For best results the light must have a minimum of 1200 w/s. The attachment ring can also be changed to fit almost any strobe head.