Actual dither size with PHD2?

I'm playing with drizzle and although I know the actual dither is random each time but it would be useful to know what the small to extreme dither size limits do.
I know in PHD2 there is a scale factor too - but I am assuming it is some multiplier of pixels, but I do not know what. Is it as simple as 1-5 guider pixels and then PHD2 scales that with its Brain setting?