ΔE 8.1, close: similar, with a visible difference side by side. Strap Grey is more muted than Dunkelgrau RAL 7021.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Strap Grey is more muted than Dunkelgrau RAL 7021.
The same difference applies the other way round: Dunkelgrau RAL 7021 is more saturated.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Dunkelgrau RAL 7021 on the colour wheel See Strap Grey on the colour wheel
All matches: Dunkelgrau RAL 7021 equivalents · Strap Grey equivalents