Yes, you can, just screw the filter onto your nd filter. But also requires an 82mm diameter 

Normal use of Heirou products will not produce vignetting and will not be affected by other lenses under normal conditions. 

No 1/2 is stronger! 1/8 - 1/4 - 1/2 etc. 

The main effect of the black soft filter is to soften the highlights. for example, soften the light effect of the actress's facial details, 2. It can effectively reduce some wrinkles and spots on the face of the actor, but at the same time maintain the details and clarity of the character's hair and eyes. 3. It also plays an important role in film shooting. Excellent black mist filter does not affect the color temperature, the use of dim scenes with a hazy age will create the atmosphere of the scene well. 

There is an outer coarse thread although I haven't tried stacking another filter. 

Hi, please refer to this video https://www.youtube.com/watch?v=GpPPwc9H0q0 which briefly showcases the difference between the three series.