Date unknown, but $5.95 got you a pair of these bad boys including postage east of the Mississippi.
Also, no zip on the address. 5 digit zip was introduced nationwide in the US by 1963. So this may be 50's or at most very early 60's.
Not gonna lie. With body armour and a full face helmet I'd want to moon walk in these a bit.
Of course, I'm not sure that's what these do; but they look like it.