A system for temporally or permanently securing a removable window well cover or grid over a window well at, for example, a construction site is disclosed using adjustable mounts. The window well cover or grid may be pivoted open and closed without having to fully remove the window well cover from the opening of the window well. The adjustable mounts may include a grid sleeve unit slideably attached to the window well cover, and a lock keeper slideably mounted on the grid sleeve unit. In one aspect, the adjustable mounts include theft-deterring features that inhibit unauthorized removal of the window well cover from the window well.