I can't remember the acronym but X-Caliber has what they said was a "lighter" medium contour, T-something-something, I ordered it but didn't write that part down.
They don't have it listed on the website but I heard Justin describing a "diamond pattern" fluting that saved lots of weight while keeping the stiffness, sounded expensive so I didn't enquire further.
The more I see of it the more I'm thinking I should order the Matrix rail from Chris.........
I'm loving my two Bushnell SMRS 1-6.5 scopes. The BTR-2 has a fast acquisition, mil ranging capability, and a nice precision dot inside the big red circle. And best of all I know they will take a good blow after having one hit the dash in a car wreck with no issue incurred.