A lateral file cabinet is a special type of product because the shell of the cabinet has a very large open front, the depth is generally only 18" and the width of most popular sizes varies from 30" to 42" - and each drawer must carry up to and more than 100 lbs. Because of these dimensions and the fact that people will eventually move these files fully loaded (in spite of the fact that some major manufacturers insist that cabinets be unloaded first), the product requires a sturdy inside structure and this is where you have to look in order to compare different makes of cabinets.
Doxasteel manufactures grade "A" filing cabinets ranging in width from 24" to 48", with 2, 3, 4, 5 and 6 openings. The linked drawings show some reasons why Doxasteel makes the finest cabinet on the market. In raw material alone, Doxasteel uses roughly 20-25 lbs. more steel in a four-drawer file than other manufacturers.