Quick-peeks, in which the officer pops his head around a corner very quickly, are used to scan large areas when pursuing an apparently unarmed suspect or as a precautionary measure. The technique leaves the officer in a poor position to react to an armed suspect at close range, and is of limited use in poor light or in cluttered areas. Mirrors and periscopes give the officer time to take a good look at something while remaining concealed; however, one is slow to react to a close-range attack. A mirror should fit in a uniform pocket; the manipulator needs to practice using it and to take care not to show his fingers to a suspect in the observed room. While a periscope is easier to use than a mirror and can afford wider angles, they are bulkier and are limited in use in low light (although lights can be attached), clutter areas, and in distance. The slicing maneuver reduces the officer reaction time when using the quick-peek as he backs away from corners and points his weapon into the area he was searching. When using the maneuver, the officer must ensure that neither his feet nor his gun stick out around the corner. The slicing maneuver can also be used when climbing stairs or looking over couches or desks. However, this technique is time consuming and physically demanding compared to the quick-peek; yet it is preferred in high-risk situations.