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Desktop apps
Smooth
Free Funktional Icons
tick
Black
48x48
Farm-fresh
32x32
Glyph
16x16 Free Toolbar Icons
ok, tick, Blue
DodgerBlue
16x16
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3D
Free Applications Icons
ok, success, Accept
24x24
Check, good, tick
LimeGreen
red, tick, yes
Check, Accept, green
One bit
yes, done, true
DarkOliveGreen