This Westcott 213cm white diffusion parabolic umbrella is the softest version. Used in standard bounce mode some of the light escapes through the material, slightly lifting the ambient light and lowering the contrast, while most of the light is focused on your subject. If you want harder light, turn the umbrella around and aim the convex side at the subject. In both modes, you can vary the light quality and output by changing the light-to-appliance distance along the axis.
You can also use this umbrella as a gauze cloth over your subject to diffuse sharp light such as the sun on the beach. However you use the Westcott 220cm Parabolic Umbrella, less is definitely more.
Characteristics
Dimensions open: 213cm
Dimensions closed: 111x8.2cm
Material: white diffuse for standard bounce mode or large soft box