I have the Plomb version, use it all the time.
Well, to update: I bought a Plomb 3/8 WF20 and another make for the 1/2 inch size.
I tested using them on the Jeep- just taking different nuts or bolts off in various locations that would need an extension- then putting them back on.
I was worried that the flex head that is NOT a universal would be an issue. Before buying, I contacted the sellers and asked if the heads were tight.
They were tight and I must say, the sellers were modest. The tools were better than I expected in condition.
In using them a bit in testing I've concluded that it works quite well and in many applications I can think of, looking over experiences in the past, I think I would prefer them over an extension.
An example: Those bolts that you break and they are hand loose for a moment, but then hit bad threads or heavy grime and get real tight on ya.
Break it, then straighten and spin it and when you get to the tight thread spot- pop the ratchet on and quickly work through it.
That's ONE example and this post is long enough, but I'm definitely glad I asked about this and tried it out, now.