The PMC-18 is a pre-packaged cluster of 24 piezoelectric-coated steel micro-flechettes loaded in a cylindrical drum cartridge for the SFL-4 'Hornet' platform. Each flechette is a slender steel needle coated in a piezoelectric polymer that generates a localized electrical discharge upon deformation — when the flechette strikes soft tissue and bends or fragments, the coating converts the mechanical energy into a micro-pulse that disrupts local nerve function and causes involuntary muscle contraction around the wound channel.

The cluster deployment mechanism is pneumatic, using compressed gas to propel all 24 flechettes simultaneously in a controlled spread pattern. At close range (under 20 meters), the cluster maintains cohesion, delivering all flechettes into a target area approximately the size of a human torso. Beyond 20 meters, the cluster begins to disperse, reducing per-target density but increasing the probability of hitting multiple targets in a group. The pneumatic propulsion system gives the weapon its characteristically low acoustic signature — the discharge sounds like a sharp exhalation rather than a gunshot.

The drum magazine holds 8 cluster shots (192 flechettes total) and is field-replaceable in approximately 3 seconds. The flechettes themselves are designed to be surgically difficult to remove — the piezoelectric coating bonds to tissue through a combination of barbed micro-texture and the electrical activity, which causes surrounding muscle fibers to contract around the embedded needle. Field medics in GLMZ refer to PMC-18 injuries as 'hornet stings' and consider them among the most time-consuming wounds to treat, often requiring sedation and microsurgical extraction.