Our Stressline prestressed universal lintels are considered to be the strongest universal lintels in Britain. They can be installed upright or upon edge. They are available in 100 x 65mm and 140 x 100mm. Designed and manufactured in Leicester, our Stressline range of steel lintels is made from 2 & 3mm thick pre-galvanised steel plate. X CLOSE All cavity, eaves and box section lintels offer a one-hour fire resistance when protected with 13mm of lightweight plaster. All cavity wall lintels have an insulated core filled with CFC free material.