I just ordered a Williams for an Accura MR-x, which I also just ordered. The "crosshair set" for CVA was out of stock, but I was able to order the fiber optic set and a card with the additional inserts that include crosshairs. I don't have any experience yet with open sights, but this seemed like the most recommended. Lyman is another company that makes them. I'm setting up the MR-X and Tc encore for co elk this year.