I bought the minirail system for my wife's Open Studios art displays. Very well made and looks great. The really important thing is to get your screws in a straight, horizontal line. The videos and manuals rather skip over this. Sometimes when you drill into a wall the drill slips and this can cause problems. If it slips up or down you need to try a little to the left or right. The position of the screws along the rail is not critical but if you are above or below the line then the clipping of the rail won't work because there is little flexibility in the metal rails. You could use a laser leveller but I don't have one. I used a 2m spirit level to draw the horizontal line and then marked off 30 cm intervals as recommended. To minimise error I first used a thin drill bit (3 or 4 mm) as a pilot hole and then finished off with a 6 mm bit as recommended. Of course the rail covers any pencil marks of the line and so the finished rail looks very professional. Fantastic product.