I have a keezer with a collar for two reasons. One being cutting into the lid and voiding any warranty if any. The other being if you have the freezer sitting against a wall, when opening the lid, you can engage the faucets and make a bit of a mess. The collar will allow you to attach things like gas manifolds, temp controllers etc. Most towers I've see also need to be cooled with some sort if fan assembly blowing cold air up into them. No need for that with shanks and faucets.