The MB-70 Hidden Casement system is a part of the window/door system of with a thermal break MB-70 produced by ALUPROF S.A. As far as the aesthetics is considered, this solution is identical to MB-60US structure. However, its advantage is the enhanced thermal insulation performance: the value of heat transfer coefficient U_f – depending on the applied profiles – ranges between 1.35 and 2.16 W/m²K. The system also comes as an option featuring  enhanced thermal insulation performance, i.e. MB-70US HI with the value of heat transfer coefficient U_f  between 1.31 and 2.0 W/m²K.

The windows made in MB-70US system have casements that are unseen from the exterior side of the building. The position of the adjacent fixed and openable windows cannot be distinguished. In the row of adjacent fixed and openable windows all the compartments looks the same. The width of window frames is small, what makes the structure look slender and light. 

Similarly to the standard solution, the MB-70 windows have the effective water drainage and ventilation system from the glass chamber and from the chamber between the casement and the frame. The ventilation and drainage holes are covered from the outside with caps made of plastics.

The characteristic feature of the MB-70US window system is that it is closely connected with the other MB systems. Adapting such a structural design allowed achieving and applying many common elements, e.g. common glazing beads, gaskets, hardware, etc.