Red Head, 25 Pack, 1/2" x 4-1/4", Heavy Duty Wedge Anchors, Designed For Fastening Into Solid Concrete, Ideal For Attaching 2 x 4, Sill Plates & Electrical Equipment, Also Good For Attaching Structural Supports To Concrete, Tilt Up Construction, Highway Rails & Posts, Electrical, HVAC & Plumbing Systems, Metal Doors & Window Frames.