Found this on the homepagen (
?????????Grad ND????????????for PENTAX K-1? | RICOH IMAGING)
11 000 yen with taxes. Approx: 74 USD
The Grad ND function is a function that gives the effect of shooting with a gradation ND filter. This is possible by taking two images with proper exposure and one with lower exposure and combining them. A normal gradation ND filter adjusts the exposure by reducing the amount of light, so it is necessary to prepare a filter according to the exposure adjustment, but the Grad ND function synthesizes images with different exposures, You can adjust the exposure simply by changing the exposure setting on the camera.
[Filter type]
Normal: Grad ND offers normal, reversal, and custom filters. It is also possible to select line (dark) or line (bright) in Custom.
Reverse: Composites so that the light is dimmed toward the bottom. You can adjust the darkest position, composition range, amount of light reduction (exposure), etc.
Custom: In addition to normal and reverse, you can select the type of filter from line (dark) and line (bright). Up to 3 files can be saved (*).
* The dimming amount (exposure amount) is not saved.