Window Glazing Glass Packers Flooring Spacers Various Sizes The correct installation of windows consists of many factors – well-chosen tools, an experienced specialist, high-quality materials. Accessories used by fitters are also one of the important elements. Every window in every building that we use every day is a lot of different kinds of details, which many people don’t even realize. Each size is colour coded for easy identification and shaped to hang from a frame fixing. Unlike timber spacers these spacers are resistant to weather changes and are waterproof.