I added this White and Silver version to my collection in 2022. Its far less common than the Black version.
You can read more about the Walbusch B5   HERE
The White/Silver version is identical to the Black version except for the compression ring that holds the twist-knob in place (see the third picture below).
It was obviously meant to be a two piece and the addition of the compression ring leads me to believe that its a later version.
This particular sample has a cracked base plate so I use it sparingly and when I store it, I ensure that the top-cap is not putting any pressure on the middle plate.