The MB-79N hidden sash system is an economical and functional solution that meets all technical requirements.  It allows you to make windows with sashes that are invisible from the outside.  In a series of adjacent fixed and opening windows, it is not possible to distinguish the position of these fields.  Thanks to this, we obtain a uniform view of all windows on the building’s façade, regardless of their function.


The MB-79N hidden sash system is a carefully refined solution.  It offers two versions of the rebate: with a type A frame – partially covering the sash, and with a type B frame – completely covering the sash, which perfectly imitates fixed windows.  The external surfaces of glass installed in opening and fixed bays lie on one plane.  Thanks to a special adaptive profile, it is possible to use frames and battens from the MB-79N base system in windows with a hidden sash.


The MB-79N hidden sash system enables the production of windows of large dimensions and weight.  These structures, similarly to the basic MB-79N window system, are characterized by high thermal and acoustic insulation as well as water and air tightness.  This system meets all requirements for energy saving and environmental protection.

Features and advantages of the MB-79N hidden sash system:


  • The structural depth of the window sections is: 70 mm (frame), 79 mm (sash).


  • The profiles have a three-chamber structure.


  • The central chamber is the insulation between the aluminum sections and is made of shaped thermal breaks 33.5 or 36 mm wide.


  • The window sash uses an innovative, reinforced, chamber thermal break, very resistant to deflection.


  • The system enables the production of windows in three variants of thermal insulation, such as MB-79N.The MB-79N hidden sas E version is the most economical solution with a single-component central seal.MB-79N hidden sas ST is a variant with a two-component central seal.


  • The MB-79N hidden sas SI structure (with the best thermal insulation) is based on profiles equipped with appropriate insulating inserts in the thermal break zone and a two-component central gasket.


  • The heat transfer coefficients of Uf window frames reach very good values, placing this system among the clear market leaders in this category.


  • High tightness against water and air infiltration is achieved thanks to the special shapes of the one- or two-component central gasket (with a cellular insulating part) and glazing and cover gaskets.


  • Closed-shaped glazing beads, both in the Standard and Prestige versions, allow for durable mounting of fillings, which greatly facilitates the creation of anti-burglary structures.


  • Internal glazing seals are deeply embedded in the glazing beads, so they are hardly visible when viewed from the inside.


  • The maximum dimensions of window sashes are: Hs max = 2.7 m, Ls max = 1.7 m. Maximum leaf weight – 160 kg.Ranges of glass thicknesses that can be glazed: window frame – from 1.5 to 44.5 mm, window sash – from 12 to 52.5 mm.


  • A wide range of glazing allows the installation of all types of double-chamber, acoustic and anti-burglary glass available on the market.


  • The use of typical “Euro” fitting grooves allows the installation of most available fittings for aluminum and plastic windows, including:modern Winkhaus aluPilot hidden fittingsWindows can be equipped with handles with a visible rosette or without a rosette.


  • The MB-79N US system is compatible with other systems, especially the MB-79N.Thanks to this, many elements can be used in more than one system, e.g. glazing beads, seals, fittings and most accessories.





MB 79Dual action (tilt&turn)0,13 – 0,450,20 – 0,320,24 – 0,59
MB 79Awning window0,11 – 0,360,25 – 0,340,19 – 0,47
MB 79Fix0,15 – 0,510,17 – 0,300,28 – 0,68
MB 79Entrace door0,11 – 0,390,31 – 0,410,18 – 0,49


The MB-79N has been designed to outperform typical thermal insulation requirements. The MB-79 N series can be used to fabricate fixed, side-hung, hopper, tilt-and-turn, and hopper-and-slide windows.





Choose a color from our rich palette and shape the windows according to your ideas.