The flag of Slovakia, adopted in 1992, is the following:
Although flags with full achievement of arms are considered a bad practice, simple shields, specially when cleverly executed like in Slovakian case, can generate very good flags. The flag of Slovakia needs to adopt the coat of arms because its plain version is identical to Russia's.
As I said, the flag of Slovakia is very cleverly executed, using only three colors and a very geometric coat of arms in a very equilibrated layout.
The Slovak flag contains the pan-Slavic colors, and is charged with an off-centered coat of arms of the Slovakia. The origins of the coat of arms of Slovakia is the Hungarian coat of arms. While the stripes were more associated with Lower Hungary, the double cross and the mounts were more associated with Upper Hungary (whose territory was similar to current Slovakia). The double cross was used at least since the Crusades, as a Christian symbol and of old usage in the kingdom. The hills represent the Tatra, Matra and Fatra chains, in this order (Tatra and Fatra are in Slovakia).
During the Revolutions of 1848 (also known as "Springtime of the People"), the coat of arms was adopted, when the red-white-green color set (associated with Hungary) was substituted by the pan-Slavic colors, by a "Slovak National Council". In the same time, the current flag (with or without coat of arms) started to be used unofficially. It was used to represent Slovakia in the Czechoslovakia, and adopted by the Nazi-client Slovak Republic. Because of the association with the nazism, the coat of arms wasn't used by the socialist regime, but returned to usage in Slovakia independence.
I hope you liked the post. All comments are welcome.