The ExpoDisc (77mm)  type_Off Camera Flash Supports up to 10kg

Supports up to 10kg

4 and 40mm f1

Nikon Nikkor-W 135mm f/5

Also included: two genuine Sony batteries

though compatibility and results will vary from lens to lens

The ExpoDisc (77mm) &nbsptype_Off Camera Flash Supports up to 10kgThe ExpoDisc is a clip on (or hold in front of) diffuser designed to facilitate setting custom white balance. Rather than hauling around a gray card, or trying to find a plain white surface, or hoping that your camera guesses correctly, you can toss this in front of your lens and lock in an accurate custom white balance in seconds. Bonus: if you actually use this on a lens with a 77mm filter thread, it can replace your lenscap. Yeah, its just a fancy