Hollow walls need hollow-wall fastening — a standard screw in drywall or plaster just pulls through, and you're left patching drywall and re-quoting the job for hardware you should have used in the first place. The toggle mechanism on these 1/8-inch bolts spreads the load across a larger surface area inside the wall cavity, so the holding strength is in the wall itself, not the thin surface material. 1/8-inch diameter is the right choice for light-duty hollow-wall fastening: smoke detectors, picture rail, lightweight shelving, bathroom accessories. Zinc plating handles indoor environments adequately. The round head sits flush when installed — clean finish on the visible side. 50 pieces in a box covers the common case where one or two aren't enough and you're not buying a contractor pack fo Stocked at Crofton Lumber and Akron Lumber.