Key Features Provides 2 to 8 Stops of Light Control Rotating Ring to Choose Degree of ND Eliminates Buying Many ND Filters Use to Create Blur & Special Effects The 77mm Variable Neutral Density Filter from Tiffen offers a unique way of maintaining total control over your depth of field and presents an efficient way to create special effects. The filter is designed with a built-in rotating ring that controls neutral density ranging from 2 to 8 stops (0.6-2.4). The heavier the density, the slower