Stock rails are the outer rails that comprise the four rails at the beginning of the switch, and unlike switch rails, they are fixed. These rails also encompass other parts of the turnout equipment. At the start of the switch, in both the open and closed positions, one of the switch rails aligns with the inner side of one of the stock rails, allowing for a change in direction. The profile of the stock rails remains unchanged and consistent, similar to the profiles of rails before and after diverging points and crossings.