Complex sentence: Lowden Guitars of this period were labelled with a slightly smaller version of the current oval label and approximately 500-600 guitars were made in each of the first three years then approximately 1,000 per year thereafter.
Split into simpler sentences: Lowden Guitars of this period are labelled with a slightly smaller version of the current oval label. Approximately 500-600 guitars were made in each of the first three years, then approximately 1,000 per year thereafter.