The plate features three restrictor guides for various play styles:

For fighting games, the circular guide gives you the same degree of control as the Seimitsu Octagonal Restrictor Guide, Sanwa GT Y Octagonal Restrictor Gate, or JLF GT-Y Octagonal Restrictor Plate Insert.  This makes it possible to perform quarter-circle, half-circle, and full 360 movements much easier than the stock square gate.  

For retro arcade games that only require up, down, left or right movement (no diagonals), the second cross-shaped guide will provide this level of control.

For even older games where only two directions are required, the third bar-shaped guide is the one you want to use!