Locking plugs to fit 3/8" Compatible Hole Diameter - 9.5 mm | 0.375 in ; Compatible Panel Thickness Range - 3.2 mm | 0.125 in. This Solid Locking Plug is used to close off extra chassis holes, wire outlets, and access holes. It is dust, dirt, moisture resistant, corrosion, and vibration resistant. Designed to fit snugly with a finger and may be withdrawn and replaced as needed. Black