The production of these valve actuation belts starts with a fabric/rubber mat that is sewn in the first operation to obtain a roll that is then mounted in the vulcanization mold with a specific tooth profile.
In the course of the following operations, different layers of rubber material and the tensile cord are applied and vulcanized together. The tensile cord (fiberglass) transmits the main tensile load and provides the belt with additional stability.
This tensile cord is a continuous material that has not been joined and therefore gives the belt its tensile strength.
Therefore, the stitching that is visible on the inside at one point is not a stability-giving feature.