That's a non-abs valve on my GA16DE to SR20DE converted NX.
My Sunny GTI came with ABS as standard and if i remember right, there are way more lines going in to the equivalent valve.
Having put the full Sunny GTI set-up on the NX: AD22VF's at the front and CL9HA's at the rear, from existing smaller calipers at the front and drums at the rear, the thing is way tail happy braking in to a corner when the back end goes light! Had to swap the MC and Booster to cure the long pedal, and i forgot about the valve...
I believe the balance is set by the FPR lookalike bolt on piece on the left of it.
Be very wary of where you source a replacement as i believe they're very specific to each model and brake set-up.
Good luck man