The Livescribe 3 smartpen was introduced in 2014 and has been very popular with users of mobile devices.
In late 2018, the Aegir family of smartpens was introduced as an effective replacement for the LS3.
The Aegir, currently available in two colours, is slimmer and lighter. It is also available at a lower price. For a very large majority of users, the Aegir is the smartpen to buy after January 2019.
Both models sync via Bluetooth to a mobile device (Android or iOS) and both leverage the microphone present in that device.