Ledger Nano S is a product of a France-based startup. It has sleek and attractive European touch to its design.Some of its core features are the backup seed key for recovery of your bitcoins, the easy to use OLED interface, and a flash drive like feel with two buttons on the side for navigating the interface.It is a battery-less device which you can connect to a PC or mobile device via USB. Here is a video guide by Harsh Agrawal on how to start using Ledger Nano S.