A method of detecting the presence or position of a first component in an article is disclosed. The first component, which has a predefined response to incident light, includes a microporous film of a semi-crystalline polyolefin and a beta-nucleating agent. The method includes irradiating the article with incident light, detecting light received from the irradiated article; and identifying the predefined response of the first component in the light received from the irradiated article to detect the presence or the position of the first component. A method for preparing a mechanical fastening component for use in an article is also disclosed. The method includes stretching a film backing containing beta-spherulites and having upstanding fastening elements to provide a microporous film backing with sufficient porosity to allow it to be detected when subjected to an inspection system comprising a light detector.