Generally speaking, there are two kinds, one is cut on both sides, cut into wedges, glue bottle to be perpendicular to the sticky surface; The other is to cut 60 degrees on one side, and the 60 degrees plane should be parallel to the sticky surface when gluing, so as to save some effort. What brand do you use, I wonder? The one I used has a dotted line on the lip, so just follow the dotted line.