Bang-Cow iin little china...

This is a Bang-Cow, Bang-Cows are one of the few weapons found to be truly effective against machine elves, discovered in the late 20th century they quickly became a staple tool used by time travlers to prevent theft of equipment and personal injury as a result of the machine elf menace.
Their effectiveness stems from the fact that they can disable machine elves while not destroying the fabric of the universe.
Don't leave time without one.