Mazda ABS pump?

[Robotnik123]

Does anyone know what this thing is (centre of photo)? It is connected to the brake fluid reservoir in my 1992 Mazda 121 DB. Is this an ABS pump, because these cars aren't supposed to have ABS as far as I can tell.
22977

[psbarham]

looks like the brake biasing valve, it reduces the pressure to the rear brakes to stop them locking up due to the lack of weight on the rear during braking

[Robotnik123]

Thanks for that!

[martin_y]

Yep, I agree. Its the Bias valve.

[Subaru ETA]

yup, thats a bias valve