It can soften the entire image, reduce the contrast of the highlights, and produce a halo, making the image soft. 

No, the rings are intended to adapt filters and other light weight accessories on the camera lens. 

Black soft filters can be used to reduce blemishes and wrinkles in people or objects by reducing the resolution of the image. They can also be used to increase contrast and create a halo or glow effect for specular light sources in a scene. 1. 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. 

hello , the filter is 100*100, so it can work with Cokin Z series filter holder 

It's been great. I have used it with my nikon 50 1.8 d lens and a tamron 90 2.8. Highly recommend it