Task: Question Generation
Input (English): By about 1910,[note 1] bound collections of empty sleeves with a paperboard or leather cover, similar to a photograph album, were sold as record albums that customers could use to store their records (the term "record album" was printed on some covers). These albums came in both 10-inch and 12-inch sizes. The covers of these bound books were wider and taller than the records inside, allowing the record album to be placed on a shelf upright, like a book, suspending the fragile records above the shelf and protecting them.
Output (English): What were early record album covers made of?