Notice the sleek, greyhound like appearance of the body. Ancient Egypt Magazine gives a close-up of this image of Set in the August/September 2009 issue:

Author Ken Moss says it is "Seth from an Eighteenth Dynasty relief in the Open Air Museum at Karnak."
Hmm, The KMT author declares it is from Senwosret I's chapel, which is from the Twelfth Dynasty. ???
But Ken Moss shows this glyph in larger context, with a Horus falcon above it: