The M18A1 anti-personnel mine fired approximately seven hundred steel ball bearings in a sixty-degree arc and was lethal at close range. Early versions of the mine were aimed using a slit-type sight, whereas later models were aimed using a molded knife-edge type sight.
Two pairs of scissor-type folding legs enabled the mine to be positioned on a wide variety of surfaces, and it could also be tied to posts and trees etc.
Each mine came with an M57 electrical firing device and an M4 electric blasting cap assembly, which initiated the C-4 charge. An M40 electrical test set, which was used for checking the continuity of the mine's firing circuit, was issued with every six mines in Vietnam. The mine and its accessories were carried in a specifically designed bag.