Each ExpoDisc is constructed of carefully selected and matched optical grade materials encased in durable anodized aluminum filter mounts. ExpoDisc Neutral White Balance Filters are calibrated to strict tolerances of color neutrality and light transmission. Every ExpoDisc filter shipped is individually tested by transmission densitometer.\n\nThe ExpoDisc is suitable for use with any digital SLR and digital video camera with a white balance function. ExpoDisc round filters are available with quick pressure release mounts in the following standard sizes: 52mm, 58mm, 62mm, 67mm, 72mm, 77mm, 82mm, and 95mm.