I was playing around at bowjackson, building some arrow combinations to check out weights and foc, and when I have to select the point insert for the arrow, the choices are listed as HO, AL and C. I assume AL is aluminum and C is carbon, but what the heck is HO? It is the only insert option for the 3-39 and below shaft sizes, and when selected, it's apparently pretty heavy. What is is?

When you order ACCs I assume they come with unibushings installed and inserts. But what inserts? Do you get to choose? Which do you choose?