 "3 in 1 Stacking Grid Light Modifier System for CANON 580EX/ 580EX II Flash Speedlite, SG-C GRID"
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The Light Modifier was designed to produce 3 different size of light spread (Small, Medium and Large) and when aligned and stacked two grids together, produce the smallest spots of light. Stack the small grid into the bezel to produce large size spots of light, for medium size spots of light just stack the larger size grid into the bezel." 
 "DSLR Matte Box for 15mm Rail Rod System D90 5D 60D 600D, mattebox (Blue)" "Buy Photography and Camera Supplies from #1 Store in Dallas | Cowboystudio.com"
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This DSLR Matt Box is compatible with any standard 15MM rail system for your DSLR rig or cage. A matte box is used to help block the sun or other light source in order to prevent glare and lens flare.  Another purpose of a matte box is to hold glass or plastic filters in place in front of the lens." 