Links:
CK4 Wired Version:
https://gett-na.com/products/ck4
CK4 Wireless + Wired Version:
https://gett-na.com/collections/glass-keyboards-gett/products/cleankeys%C2%AE-ck4w
CK5 Wired:
https://gett-na.com/collections/glass-keyboards-gett/products/ck5
CK4 Wired Version:
https://gett-na.com/products/ck4
CK4 Wireless + Wired Version:
https://gett-na.com/collections/glass-keyboards-gett/products/cleankeys%C2%AE-ck4w
CK5 Wired:
https://gett-na.com/collections/glass-keyboards-gett/products/ck5
These are the quietest keyboards ever decibel-wise because they have no moving or mechanical parts.
They use capacitive-touch technology.