Not a tie-off cleat as one would use with rope, but a device to affix electrical wire or cable to a surface. From Cooper Industries CTCC-10.pdf :
http://www.engineerlive.com/media/images/In-situ2.JPG
Sometimes called a cable clip (again, not to be confused with the wire rope clip.
Cooper B-Line Cable Cleats are designed to support and retain your cables within your cable
tray system in everyday conditions.
http://www.engineerlive.com/media/images/In-situ2.JPG
Sometimes called a cable clip (again, not to be confused with the wire rope clip.