These belts have had various part numbers over the years but they are all the same size: Hoover 49258, 049258AG, 40201048 and Style 48 belt.
Brush roller belt for the Hoover Convertible, Hoover Decade 80 and Decade 800 upright vacuum cleaner series.
Hoover package 40201048 contains 2 belts.
When installed correctly this belt looks like the number eight. Belt is rounded, not flat.