The 33L is the same size as my Salsa Air and that thing is tiny comparing to all the carryon I have seen other people carrying. The only diff between 33L and 35L is the depth 8" vs 9". 9" is the limit and the United sizer is about 1" bigger.. around 10" and either one will pass with flying color. It is the width that's is over the 14". But both 33L and 35L has the exact same width at 15.7". I have placed my Salsa Air into the United sizer and it doesn't really stick out on top. That sizer is much much deeper than 14" I guess.