The Kestrel Elite Weather Meter with Applied Ballistics which has been referred to as the Kestrel 5700 Elite is an updated version from the Discontinued Kestrel 4500 Applied Ballistics Meter in November of 2015. Functionally you're not getting more environmental or ballistic features. So don't feel the need to upgrade unless you find the other exciting changes necessary. With the Bluetooth Kestrel LINK model you'll want to download the Kestrel LiNK Ballistics app to your smart phone to load your guns / ammo to the meter. The new Kestrel Meters with Bluetooth include the software necessary to communicate wirelessly at a range of up to 100 feet with a clear line of site (walls or obstacles will effect this range).