Protein Feeder Tube Question

I bought one of those protein drop tubes at Academy to put on a barrel feeder I have, and have never had a protein feeder. I'm wondering how far off the ground are the feed openings the deer eat out of when mounted? I'm guessing around 40" or so but not sure. Thanks.

40 is good.

38" is where most of them are placed...I prefer lower than that at around 33"-35" to the bottom of the tube or port opening. Deer can eat much easier if it is a bit lower.

Thanks!