Usage Tips:DRILL STRAIGHT -- It projects a series of circular patterns on the worksurface that indicate alignment or misalignment of the drill bit with regards to the worksurface. When the patterns are concentric, the drill is straight with (and perpendicular to) the worksurface. ANY ORIENTATION -- It works in any orientation, so it can easily be used on walls, floors, ceilings, or boards at any angle. The Cores unique shape also allows it to be virtually invisible during drill rotation, so the drill bit, worksurface, and the Cores projected worksurface patterns are clear and easy to see. SAFE TO USE -- It safely disconnects if an obstacle isencountered during drilling operations. WORKS WITH YOUR DRILL -- It was designed to work with thousands of common standard electric drills and drill chucks. NON CONTACT -- Unlike traditional drill guides, drill cups, or drill blocks, It does not need to contact the worksurface you drill into, and thus will not scratch or mar it during normal operation. Further, unlike traditional drill guides, drill cups, or drill blocks, It does not block or obstruct your view of the drill bit or worksurface during a drilling operation.