I run Tanabrex on the rear and a MK on the front of my ZCO. I prefer the way the Tanabrex lays flat so I can see my dials. I tried the MK set, but after a few range trips, like mentioned already above, the weaker spring causes the scope cap to flop around, especially in the wind. If they just tweak the spring tension, they'd have a winner. Other than that, they're a great overall design and look and function great.