# What does anchors' scales actually refer to in Faster RCNN?

I am trying to understand the faster RCNN but I can't understand the meaning of anchors' scales? Especially in this article Faster RCNN.

The author considers 3 scales $$(128^2, 256^2, 512^2)$$

What does this line mean?

I know that for each $$3*3$$ spatial location in the feature map (VGG) we perform convolution and after that we do conv for each anchor box. the receptive field of those $$3*3$$ spatial locations are $$(16*3)^2$$ in the original image and I think that that means the anchors area should be smaller than $$(16*3)^2$$. Isn't $$512^2$$ too big for an anchor? What happens when it's near the edge of the original image?