ITEM NAME:300mm(12'')Adjustable Engineer Combination Try Square Set Right Angle Ruler #gib Store Home Promotion Hot Item Add to Fav.When you want to move your handle, firstly loosen the nut and pull it down, let the handle loosen with the ruler, and then you can succeed. For a 90 degree Angle between the ruler and the handle, after the upper plane of handle and the ruler are parallel, then tighten the nut.