I sometimes find the expression "only one" in Japanese manufacturers' catalogs.
E.g., "We produce only-one products exclusively designed for respective customers, thus supporting their production sites and contributing to society."
Is this expression English?
Should it be replaced with "unique"?
- We produce one-off products exclusively designed for individual customers, thus supporting their businesses and contributing to society.
"production sites" is correct English but sounds strange to my ears. You could say something else like "factories", "workplaces", or "offices" as appropriate.