577 and 657 are the names of two trees in the historic gardens of Bad Homburg. Around each of these two trees is a circular metal ring. The two rings are painted with different flip flop colours high gloss. One in red/cyan blue, the other in blue/purple/red/coppery. Flip flop painting uses the principle of polarization, where certain frequencies of reflected light- and thus the different colours within the paint- are strengthened or weakened depending on the viewing angle.