Prussian three-class franchise
The Prussian three-class franchise (German: Preußisches Dreiklassenwahlrecht) was an indirect electoral system used from 1848 until 1918 in the Kingdom of Prussia and for shorter periods in other German states. Voters were grouped by district into three classes, with the total tax payments in each class equal.
Source: Wikipedia — Prussian three-class franchise (CC BY-SA 4.0)