This is a faucet connector by Fluidmaster from the Fluidmaster No Burst product line.
The connector hose is made of metal mesh and has a 3/8" female compression thread on one end and a 1/2" female pipe thread on the other.
It measures approximately 12" long with the mesh hose portion measuring approximately 1" in diameter.
This faucet connector comes in great pre-owned condition with the original tag.