The door of this case was in a detached one-storey house having access to the garden. The frames of the house had external wooden sliding shutters and internal two-piece sliding recessed glasses.The “jamb’s” space between the wooden shutters and the glasses were 5cm. So the use of a retractable steel gate was the best solution because the width of the frame is no more than 4cm in the steel retractable door.It was designed as a double leaf construction – without the use of hinges for best rotation – as the existing frame of glasses, so that opening and closing the door by the right and left side it should not hinder the passage.The width that “folds” the door from both sides is 23% of the frame’s width divided by two (because it is a double leaf).The choice of colour was the customer’s choice in Ral colour of powder painting in shades of grey.The customer chose to secure his house with retractable steel gates because they were exposed to the danger of burglary, since this was a one-storey house, he could not enjoy the views of his garden and even could not open the doors to ventilate his residence.That way there was no need for any special repair or preparation on the existing frame, we put the retractable grille with code type T90 – which is a galvanized steel construction – designed to allow natural ventilation from the right and left releasing the 77% of the width of the frame and providing security and confidence to the client, who made this particular choice.