Because of a special coating containing a high number of reflective aluminium particles, ALU42 THERMO slats reflect the heat from the house. The static layer of air between the window and roller shutter is further heated, resulting in a higher insulation value. The aluminium coating is either on the concave or convex side of the slat, depending on the roll-up (surface-mounted roller shutter or built-in/built-on roller shutter construction), but it is always directed towards the external joinery. Foamed slats provide extra strength and more durability.
*The higher the R-value, the higher the insulation value