It is extremely critical that when attaching the suction cup to FIRST LIFT THE LEVER ABOUT HALF WAY before attaching to the glass in order to only apply about half the suction the tool is capable of applying!! Lift the lever half way. Set into position on glass. Lift the rest of the way to apply about half of the suction cup's potential suction. Failure to do this WILL result in circular break around the suction cup!