Originally Posted by
jerseytom
To be more specific, using
this product page as an example, they go so far to specify...
"
The Maxlite® 5 Expandable Carry-On Hardside Spinner is designed to meet carry-on size restrictions for most domestic airlines while maximizing how much you can pack inside with its convenient 2” expansion option."
"This Carry-On bag has been sizer bin tested to accommodate overhead bin space on most major US airlines."
And yet, overall dimensions listed: H: 23in W: 14.75in D: 9in
AA / UA / DL all state 22 x 14 x 9 max. Like how could someone say, "We tested this on most of the major US airlines... just not United, Delta, or American" 
Given the size limitations of those US domestic airlines, sounds like it wasn't very well designed then