It would be best to go up in height from your current setup if you find it to low. We measure from the top of the rail to the center of the optic. For instance, our mediums are 1".
We recommend a set of Extra High (1.5").
As long as you match the correct tube size and height for your optic and have a 1913 Picatinny rail with at least two full slots at each ring they will work.
The correct ring height will also depend on the barrel contour and scope base you are using. However, the objective lens outside diameter is 2.32" on the Arken SH4 Gen 2 6-24x50mm scope. So the MDT Premier Scope Rings 34mm 1.25" high rings will provide enough clearance.
The MDT Premier Scope Rings are measured to the centerline of the scope rings.
I recommend using the 34mm extra high MDT Premier Scope Rings for that scope. The objective lens outer diameter is 2.3" and the centerline scope height of the extra high rings is 1.50". So they will give you enough clearance. The model number you need is 103550-BLK.
To mount the Vortex Strike Eagle 5-25x56mm Rifle Scope on a CZ 455 Varmint, I recommend using the 1.50" high 34mm MDT Premier Scope Rings. You may be able to use the 1.25" but to ensure enough clearance with the 56mm objective lens I recommend using the extra high rings.
According to the manufacturer you need a 9/64 Allan Key.
I recommend using the High 34mm MDT Premier Scope Rings.
You would want the 1.5"/extra-high rings.