This revolutionary friction fit seal increases acoustic performance of a standard fire rated door simply and effectively. Its design is based on ‘dual air pocked technology‘ which acts in the same way as double or triple glazing. The NOR 710FR also has smoke seal capabilities in accordance with BS 476 Part 31:1 and is unaffected by door furniture including hinges and latches. We have cycle tested the NOR 710FR acoustic seal up to 100,000 opening and closing cycles. CF 629
 

The recommended gap tolerance is 3mm - 4mm.