Two Sided Material Node

Front – The material which is used for front-side faces as defined by the object normals.

Back – The material V-Ray uses for back side faces as defined by their normals.

Translucency – Determines which side (front or back) relative to the camera is more visible in the rendering process. By default this value is 0.5, which means that both the side facing the camera, and the one facing away from it, is visible to the same degree. When this parameter is closer to 0.0 the more of the material facing the camera is going to be seen. When it is closer to 1.0, the more of the back material is seen.

Force Single-sided Sub-materials – When enabled (the default), the sub-materials renders as one-sided materials. Turning this option off is not recommended.

Multiply by Front Diffuse – When enabled, the translucency is multiplied by the diffuse of the front material.

Material ID – The color used by the "Material ID" render element. You can also use a shader here.

Multimatte ID – The integer ID of the material to be used by the "Multimatte" render element.

Round Edges Enabled –  Enables the round edges effect which uses bump mapping to smooth out the edges of the geometry during render time.

Radius – Specify a radius (in world units) for the round edges effect. Since the actual geometry is not being changed and only the normals of the faces are affected, large values here may produce undesirable effects.

Consider Same Object Only – When enabled, the rounded corners are produced only along edges that belong to the same object which has the attribute applied. When disabled, rounded corners are produced along edges formed when the object with the attribute intersects other objects in the scene. 

Corners – Choose which edges are considered in the calculation. Possible options are:

Covex and Concave – Considers all edges. 
Convex Only – Only applies Round Edges effect to edges with convex angles. 
Concave Only – Only applies Round Edges effect to edges with concave angles.