Using Gimp 2

Does anyone know how to set the radius for Blur in Gimp 2.

Going through Enhance there are lots of settings for Sharpen, etc., but I cannot find settings for Blur.

 

Hello,
You can use Radius in Selective Gaussian Blur.

 

Thank you very much. I'll see what I can do with that.

I should have asked my question differently and asked about the underlying issue and an assumption I made. I have now seen that blur reaches outside a selected area. My assumption was that it does this to the same degree as the radius inside the selected area - which may not be true. (That it should blur outside the selected area at all makes no sense to me, but it does it.)

This is my specific problem. I blurred an image heavily inside a certain image edge (slightly away from the edge itself) and the blur reached outside the selected area and wiped out the sharpness of the edge. If it is not the radius that does it, what then?