The Lionel KW transformer was the second largest transformer Lionel made in the postwar era. It delivered 190 watts of power and provided two handles to control two trains. Internally, the design is very similar to the ZW. If the ZW was Lionel’s Cadillac transformer, the KW was the Buick. I always thought Lionels were overrated until I ran a 675 locomotive with a KW.
There was a time when nobody made modern transformers the size of a KW or ZW. Now that they do, the ZW and especially the KW cost a lot less. I remember when a reconditioned KW cost $200. Today you can get one for under $100. An as-is KW with minor issues will cost half that. These days, the KW is a bargain.