Usually, the "keyhole cover" or "rose" has become part of the lever or knob and is added to the door accordingly. For steel products, keyhole covers follow the size and proportions of the glass cutouts used for the hardware, and take various forms according to the final design of the door.

When designing a door for a project, there are many choices about how to handle this projection. When the door has only one large hollow glass panel, the range of selection is actually only the size of the entire keyhole cover relative to the ratio of the door. When the glass fragments on the door are separated, the choice becomes the relationship between the keyhole glass and the glass fragments.

The balance between the use of eyewear, TDL and its relationship with the lever height has become a design challenge. In many projects, the streamlined shape, keyhole cover and lever position became the driving force for the horizontal alignment of all doors and windows throughout the project.