Features:1Device for measuring the changes in distances between points in solid bodies that occur when the body is deformed.2It is used either to obtain information from which stresses (internal forces) in bodies can be calculated or to act as indicating elements on devices for measuring such quantities as force,pressure,and acceleration.3Suitable for all transparent lens and coloured lens.Specifications:Structure: as describedItem name: Lens stress detectorElectric Voltage: 220V/50Hz: 15WVolume: 115 x 8 x 13cmPlug Type: EU Plug,it applies to Indonesia, Germany, France, Spain, Italy and so on.color: Whitematerial: plasticPackage Contents:1 * Lens Stress Detector TesterOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.