Upper section with clamping ring for unscrewed (Class A / B) covers of chamber systems, with sludge bucket hanger (accessory art. no. 860115), continuously height-adjustable by 500 mm (Comfort chamber system) or 450 mm (standard chamber system). If installed in roads, parking areas and comparable hard-surfaced traffic areas for trucks (Class D) the upper section must be underlaid on site with an 18 cm thick reinforced supporting slab, 2.30 x 2.30 m, made of B25 concrete. The exact design of the concrete slab must be calculated structurally according to the circumstances on site. A standard formwork and reinforcement drawing can be provided. An embedded step (art. no. 860109) must be installed if the allowable difference between the top of the chamber cover and the first step is exceeded.