The Mag-Tek range of pre-focused grids comes in a standard specification: 85 lines per inch (lpi) with a focus ratio of 8:1. Pre-focused grids give the best results since the shadows produced by the lead strips are minimal. This applies even if the source of the X-Ray beam is not positioned on the focal point of the grid. The grids are designed to allow them to be snapped onto the cassette. All our Grids come supplied with a Perspex cover and Locating Frame.