All Clack control boards made before 2014 will only work with this AC transformer.
And the 3 button TC boards made before 2017 will only work with this AC transformer.
All boards made AFTER 2017 ( and some after 2014 ) will work with either the older AC transformer,
The AC transformer is no longer being made ( as of July 1st, 2021 ),
but we should have a enough to continue providing them for several years to come.
When the available stock gets "LOW",
we will mark the Availability as "Limited Stock",
and will provide our current ( remaining ) stock level in the product description.