This black plastic yo-yo, slightly larger than standard, is in fact a miracle of miniaturized engineering. When it is activated using a concealed switch, it acts as a winch, winding the cord back around the axle. It is intended to clip on an agent’s belt for use as a climbing aid. One half of the yo-yo contains the micromotor array, made from super-tough carbon fibre components bonded together at the molecular level. A complex micromechanical gear system delivers up to 350 watts of power. The other half houses the highly advanced lanthanum/nickel/ tin battery, which supplies as much current as a car battery yet fits into less than a tenth of the space. The battery holds enough charge to let the motor run continuously for one hour. When it is due to be recharged, the agent needs only to use the device as a yo-yo; the spinning motion runs a tiny generator in its core and will charge the unit fully in approximately fifteen minutes. The shell of the yo-yo, including the belt clip, is made from stress-resistant polycarbonate. The cord itself is made from an advanced form of nylon that can lift weights of up to one hundred kilograms. Thirty metres of it are wound round the central axle. Because the yo-yo may have to be used as a toy, either to recharge the battery or to pass inspection, it has been designed to function normally despite the unusually long cord; this has been achieved by using a pair of axles, inner and outer. When the yo-yo is dropped, the cord pays out to a length of one metre before the outer axle locks in place. The two sides can then spin around the inner one. Pulling the cord harder unlocks the outer axle and allows the entire thirty metres to unwind.