Black background for SS or any German tank-crew (Heer or SS).
Circle with a star — for Oberschütze (senior shooter).
Angle on a triangle patch — for Gefreiter (private 1st class).
Double-angle on the triangle — for Obergefreiter (like senior lance-corporal).
Patches on dark-green background were introduced in October, 1936. Later 1940 they were officially replaced with the same but on Feldgrau cloth (main uniform colour).
Waffen-SS used the same chevrons but on black. All tank crewmen had also black arm insignia.