From their website:
“Welcome to our comprehensive guide to the 1930 census. Learn how the census was taken, which records survive today, and how to find microfilm that may contain your family's records.
Our microfilm locator
·is not a family- or individual-name index or a digital version of the original records.
·contains the microfilm lists for the 1930 population schedules and the Soundex indexes, searchable by over 120,000 geographic locations.
·allows you to know before visiting NARA exactly which roll(s) of microfilm you need to view, rent, or buy to start your research.
·is a good place to begin your census research. Only by viewing the actual microfilm rolls will you be able to complete your research.”