This vintage Kenner Star Wars Snaggletooth Engineering Pilot comes directly from the very first batch of examples of the action figure sent to Kenner in 1978, after the company realized it's error in creating the taller 'Blue' Snaggletooth version of the action figure.
Kenner's Test Lab put this first batch of figures through various reliability and QC tests, before approving it for release to the public.
While the figure is dated, and very much a production quality toy, it and others from this initial batch were never made available to the public.
A Kenner testing engineer marked the figure's feet with the letter 'U' and number '5' signaling that it was an 'un-gauged' test piece, and figure number 5 from the test batch.
Legitimate EP figures are extremely tough to come by, and this example grades an unusually mint AFA 85. Few EPs survive the testing process in this kind of shape.