Special Drawing Rights (SDR) are the International Monetary Fund's reserve unit, used in international aviation to state minimum liability insurance amounts. Regulation (EC) 785/2004 requires 750,000 SDR of liability cover for aircraft of 20–25 kg take-off mass — roughly €900,000, with the euro figure floating with the exchange rate.
For a hobby drone under 20 kg, the SDR figure matters only as background: the practical insurance minima are set by national — Latvian — rules, not by the European regulation's SDR thresholds.