The self defense machine is a pair of robotic arms made of high-grade titanium. The forearm segments are equipped with rounded plates to deflect blows, while each finger has a sapphire claw. They can be worn as armor mounted anywhere else on the body as extra bodyparts (the later requires physiotherapy and surgery). The SDM was created by a scientist during the year 5731, but only the prototype remains.
The when worn as extra limbs, the SDM can extend itself through hydrostatic tubes to a maximum length of 5 meters. There are also hidden blades that can be everted from the palms of the gauntlets. As with other prosthetics, mastery over their motor functions requires training.