Brooks Guide Rails are different than the traditional posting you see from different running and motion control footwear out on the market. With Brooks Guide Rail technology, the idea is to take pressure off the knees and ankle while allowing a softer feel under foot. This helps to stabilize pronation along the inner wall of the guide rails while providing limited movement to the outside of your foot with the outer wall of the guide rails. The image below shows the greenish inner wall and the bluish outer wall. The bluish outer wall is shorter as it focuses only on the movement of the heel while the longer greenish inner wall provides the stability throughout the arch. In Between both of these two guiderails or walls you can see where the heel sits directly on the shock absorbing white foam in the middle. This is advantageous for the wearer since sitting directly on this foam will be a softer experience compared to a traditional firmer post in other footwear.
The shoe below shows a traditional posting method on a shoe. If you look at the medial side of the shoe along the arch, material directly underfoot is usually a different color, indicating a different material. In the Rear View, the post is higher on along the arch of the foot compared to the outside of the foot. A traditional post typically us made from a firmer material. This firmer material along with the increased height on the arch side helps stabilize the arch and prevent pronation to help with alignment of the foot.