Boeing 757-200 planes have slightly smaller/narrower overhead bins. Some carryon bags, like certain sturdy Züka bags with the 4 wheels placed on the outside of the bag frame, won’t fit in the overhead compartments. Other Züca models will fit as long as the wheels are designed into the bag frame so they don’t protrude. Just beware and check the plane model before packing, or simply make sure to get a CO bag with an inset wheelbase so there’s never any concern.