Definitely Williams made.
As far as I have personally seen, Williams Kobalt Ratchet numbers were
02030 - 1/4"
03030 - 3/8"
03031 - Long 3/8"
04030 - 1/2"
As a good rule of thumb, any Kobalt ratchet, socket, or wrench that is 0#### is a Williams made part. The Danaher parts are usually...