Complex sentence: Möller also built a large number of theater organs (often known as the "Möller Deluxe" organ) and the company's largest theatre instrument still resides in Atlanta's Fox Theatre, affectionately known as the "Mighty Mo" since 1929.
Split into simpler sentences: Möller also built a large number of theatre organs, often known as the "Möller Deluxe" organ. The company's largest theatre instrument still resides in Atlanta's Fox Theatre, affectionately known as the "Mighty Mo" since 1929.