Hands on with Kairos see-through hybrid smartwatch

US-South Korean start-up Kairos is showing off a smartwatch that superimposes notifications and other graphics over its mechanical parts.

The design means that even if the transparent OLED (organic light-emitting diode) screen's battery runs out, the device will still continue to function as a normal watch.

It is, however, heavier and bulkier than typical timepieces. The starting price is $1,190 for the basic edition, and can go higher if the user wants more accurate internal Swiss-made mechanical parts.

The BBC's Leo Kelion met Kairos chief executive Sam Yang at the Baselworld trade fair in Switzerland, where the watch is on display, to see how it works.