Dave,
Your Master Mechanic set appears to be Easco sourced. If so, should be a quality set..nice find!
Crtdi- my humble thanks, you have many nice sets!
I like the 1/4" best of the RHFT. The 4 current other RHFT I have, plus two I gave away in the past, were all QR.
The set is kinda odd. 3 largest sockets have detents, spinner does on male end but not female, extensions have a hole drilled in 1 side to be a detent. I figured the set to be 80s. Spinner doesn't have a thru-shank but 2 metal pieces like old Plomb spinners.