A "1 of 1" Casa Wallet would be the same as saying a "Single Key" Casa wallet.
In the Single Key setup, there is only one key needed to sign and send transactions. This is great for storing and using small amounts of bitcoin in a lightweight wallet that you want to use "on the go."
This is not a multisig setup, and the Single Key should not be considered to be highly secure next to a well-designed multisig solution that Casa offers.
We offer the Single Key to all membership levels, from Silver on up.
For more info, see our article on Casa Wallet.