Complex sentence: The Cloos Company continued to make fifes up to 1946, when the company was sold to the Penzel Company, then later Penzel and Mueller, which continued to make fifes under the Cloos name.
Split into simpler sentences: The Cloos Company continued to make fifes up to 1946, after the company was sold to the Penzel Company. It later became Penzel and Mueller, which continued to make fifes under the Cloos name.