@ernesto None of the bars that are supposed to be mounted by the user comes without holes on its sides. By the way, if you need to ask the missing one to the customer service, check also the bars that you have for any damage: my Ender 3 V2 came with a small bump on the Y rail, and I just had to flip it over to make it work, but you definitely don't want to receive the spare part you were missing, and realize you need one more spare part.