History of Hoover Attachment Hose for upright

[frkirby511]

Here's a question for all the Hoover experts: why did the Hoover change the design of the hose ending from the early 1930's when it had the curved design, to the completely straight end which went from the Model 150 through the Model 63 early version?

The later version of the 63 all the way through to the end of the convertable run had attachments with curved handle grip on the hose.

Just wondering.