The CPK-5 consists of a hardened polymer-ceramic knuckle guard housing four resonant emitter nodes, one positioned behind each striking surface. On contact, each node fires a microsecond burst of focused ultrasonic pressure into the target tissue, generating localized cavitation bubbles within fluid-rich biological matter — blood, synovial fluid, vitreous humour. The bubbles collapse almost instantaneously, producing secondary shockwaves that shred tissue from the inside without requiring deep penetration.

What distinguishes the CPK-5 from other percussion-class melee weapons is its selective tissue targeting. The ultrasonic burst frequency is tuned specifically to biological fluid densities, meaning it passes through synthetic augmentation casings and subdermal armor plating with minimal attenuation before detonating inside the soft tissue beneath. Heavily augmented targets — who might otherwise shrug off conventional strikes — are often more vulnerable, not less, as their augmentation infrastructure traps and amplifies the cavitation event.

ZHENG-DAO BIOELECTRIC originally designed the CPK-5 as a 'non-lethal compliance tool' for corporate security, but field reports quickly revealed that repeated strikes to the torso caused internal hemorrhaging, organ rupture, and in several documented cases, vitreous detachment leading to permanent blindness. The 'non-lethal' designation was quietly removed from marketing materials after the third wrongful death settlement.