Feeding tube shape is only ever so slightly curved on one side so It is exceedingly easy to put in in the wrong way.  You can put it in and push it most of the way down, but you won’t get it out again!!!  Happened 2 of 3 times and now unusable.  That’s a disgrace for the price they charge!  Why not have a more significant shape difference that’s impossible to put in wrong or rather why is there a shape difference at all?