Is this symbol the 'tensor product' or the 'outer product'?

Question

I need to compute the centroid of 3D polygons that are either triangles or quads, I found the following formula but I'm not sure about the meaning of the symbol in the last formula:

Centroid of a 3D shell described by 3 vertex facets

Is this the tensor product, the outer product, or something else ?

Answer 1

The meant product is the cross product. No Problem :)