Gray side: Reflectance 17.8%; Density 0.74 | for Max. deviation of reflectance: 2% | for Max. error in exposure measurements: 1/8 of F-stop | This handy double sided pop up 18% grey/white card simplifies the complex technical issues surrounding exposure and color correction when working in different lighting conditions. It provides a major benefit when working under pressure at events such as weddings or fashion shows. | Backed with Lightdow 90-Day Hassle Free Return & Replacement Warranty for Quality-Related Issue.