The lit Touchdown and Positioning Marker (TD/PM) Circle is superimposed on the yellow painted marking. It comprises a concentric circle of at least 16 discrete lighting segments. The elements have a width of 100 mm. A single circle is positioned at the mean radius of the painted circle of the Helideck. As stated in CAP437 the lighting segments provide coverage between 50% and 75% of the circumference and are equidistantly placed with the gaps between them not less than 0,5 m. The mechanical housing is yellow powder coated and grip coated.