So, I just found out there is a specific hha tetra xb for the sub 1. I had no idea until I did a google search and found it on wyvern's web site. It replaces the scope rail. Very interesting option for me, that and a nice 4-16 or so sfp with ao scope sounds like it fits the bill. As I do not plan on hunting with this crossbow, low light less important. I have seen some nice scopes that fit the bill under 200.