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The height of your scope rings will depend upon the diameter of the objective lens bell of your scope, and possibly the mounting location of the scope. On the pictures you provided, the scope is mounted forward so that the safety is behind the rear of the scope, thus allowing room for your fingers to get enough leverage and clearance to turn the safety.
It would seem that there are a lot of these "sniper" safetys coming on the market. Trade-Ex here in Canada is offering them for sale at $35 each.
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