Stainless Steel T Ruler, the material of the ruler is very thin, the setting for T has 2 screws that hold the ruler to the plastic and it not 90 degree aligned. You need to loosen the screws and use a tool to align them. The holes are tiny so only a mechanical pencil will fit through to make marks. It has 1mm and 1/2mm holes which are larger and 4 1/4mm holes which are almost impossible to use. exactly, these are small sizes)