Mattel is (or was) a contractor for M16 parts - I have first hand experience with this as my M16A1 that was issued for OSUT (Basic and MOS School rolled into one) had, you guessed it, a Mattel grip on it. Believe me, I was shocked when I saw this - but as long as the rounds hit what I aimed at, I didn't care too much in the long run.
Spark