Abstract: A device and method for determining a tension factor in grids such as tennis rackets and the like, which have different sized string areas, the device including a frame structure defining a fixed, predetermined test area within a larger size racket string area and having a mechanism for relating two measurement components, a deflection component and a force component, an element for applying a first measurement component to the grid test area and an element for sensing the other component resulting from the application of the first component, and determining from the two components a tension factor in the strings forming the grid, the method including defining a predetermined test area within a larger grid area, applying one of two measurement components to a portion of the grid test area, determining the other component resulting from the application of the one component to the grid test area, and determining a tension factor in the strings forming the grid from the values of the two components; the apparatu