Sscrew shield for the MEGA 2560? Or how to interface wires permanently?

@CrossRoads That's along the lines of what I am looking for.

I find a Mega Screw Shield, 98 screw terminals.
A Larger Screw Shield which looks like it just covers the double row of pins (22-53 and power)
But I'm not finding the medium one.

In the Mega Screw Shield options photo what's the grid used for in the second picture. A - L and 1 -15?