This creative soap shelf is made of PP plastic and the suction cups are made of rubber and ABS plastic.Guarantee never rust, proved by 24-hour Salt Tests.Suction works best on,non-porous,sooth and flat surface,such as ceramic tile, glass, mirror, stainless steel, acrylic, etc.Suction will not work over grout lines or on porous surfaces such as: wood,unfinished marble,granite,porcelain, wallpaper, natural stones (such as travertines ), painted wall & any surface that is bumpy, etc.With the suction cup technology, it becomes extremely easy to install soap shelf: simply position on a smooth surface, apply pressure and turn clockwise.It can be as a good gift for promotion.And can print your LOGO on it.