A scanner ring is a worn device, a ring on one finger of the human hand, which is a barcode scanner. It is the smallest but also typically the least reliable and most expensive device that can scan barcodes. It is also innocuous and can be used without anyone noticing, so it has advantages in unfriendly retail situations where use of Consumerium Services may be forbidden or discouraged. Are these critical performance requirements?
It could also innocuously link by wire to a wrist device on the same hand.