The Freeland Fork was intended as a portable rest for M21 rifles. It is simply a cast aluminum piece with a fork on each end. The narrow end was put into the ground and the rifle was rested on the wider end with the rubber coating. Although an interesting concept, these forks were not particularly effective and not widely used.
Both forks pictured are aluminum but have different finishes. The darker one is marked "USMC". The lighter finish appears to be bare aluminum.
See Peter Senich "The Long Range War" page 143.