It is a Plomb WF-21. I have two unmarked like yours and two or three marked. Have some in other drive sizes as well that are unmarked. I have no idea why they left them unmarked but it is common.
Plomb did some strange things sometimes. It seems virtually every ratchet I come across has some difference. Sometimes the markings, sometimes the size of the logo, sometimes the plomb bobs directions, sometimes differences in the forging dies. The selector switch sometimes are different too. Sometimes they face the drive lug sometimes they face the handle.