Oak 90 is a kit winder staircase designed by Fontanot and made of painted steel with solid natural oak treads. The handrail is made out of PVC with an aluminium core and is available in a colour to match that of the staircase. The railing consists of white painted balusters. The going is adjustable from 18 to 22cm (for 70cm treads) and from 22 to 26cm (for 80 and 90cm treads). The supplementary balustrade that protects the opening on the upper floor comes in 120cm modules with 10 balusters and a handrail. The supplementary external railing is composed of 5 balusters, a handrail and fixings, and is used as protection if the outside of the staircase is far away from the wall.