Hario V60 Drip Scale
Hario V60 Drip Scales are almost synonymous with Specialty Coffee. I'm sure every barista has owned a set at some point, and likely still uses them daily.
With 0.1g accuracy, it gives you total control over your coffee to water ratio which is essential for a perfect home brew. Alongside this, the integrated timer ensure you can time your extraction without taking your eyes from the pour.