Wearable computing. Laser ring scanner being used to read a bar code on a cardboard box. As the scanner is on a ring, the operator's hands are left free to carry out other tasks. Data may be temporarily stored on an arm-mounted wireless computer (not seen) which is connected by a wire to the scanner. The computer, which is powered by an 8 hour battery, has a four line display screen and keyboard. The scanner can read bar codes from up to 60 cm away and weighs just over 50 grams. This ring scanner system was developed by Symbol Technologies, USA.