Stumbleupon Icon - ICNS Format.

512 x 512
Stumbleupon icon 256x256Download
256 x 256
Stumbleupon icon 256x256Download
128 x 128
Stumbleupon icon 128x128Download

64 x 64
Stumbleupon icon 64x64Download
48 x 48
Stumbleupon icon 48x48Download
32 x 32
Stumbleupon icon 32x32Download
16 x 16
Stumbleupon icon 16x16Download

More icons from the Social Icons 2012 icon set: