Here’s a comparison shot of the 6159-7010 and the SBDX005, a reissue of the 6159-7010. They appear to be about the same size in the picture because the 6159 is slightly in front. The SBDX005 is actually bigger than the 6159 by 1mm.
On the 6159, the lume ball on the second hand overlaps the round hour marker making it difficult to find the second hand in low light condition. On the SBDX005, the lume ball is moved in a little to avoid the overlapping the hour markers. It even fits nicely into the space between the ‘600m’ marking and the 6 o’clock marker. Picture below illustrates the above points.
Click on the image to see full size picture