400.
I believe that the S-263045 is for solar
and has a drain down when off.
Edit. I was thinking about the valve and not the actuator, but when I did a search for S-263045, it came up with a link to a solar actuator. But.. as far as I know there is no difference between a solar actuator and a standard actuator.
So to directly answer your question, I have no clue what the difference is...
Jim R.