Talk:Sans/@comment-24601134-20151118204220/@comment-26696343-20151120023929

Lefty trombones are custon instuments. While a normal one can be put together backwards so the slide is on the left, this messes with the spit valve and is not recommended if the player plans to move on to other instruments in the trombone family.

That being said, we have no idea how well Sans can actually play his trombone, he probably found it in the dump and can only play the 3 notes you hear in game! (How he plays without lips is another question...)