80s Retros 1989 Silver Dustproof

Hey look it's KTT Retro Silvers again, except they got a tan. These are weird, I think they came out before the KTT Retro Silvers, but the names are of course very similar, and both come in a normal and dustproof stem. I wonder if KTT "borrowed" this design from 80s Retros when they saw it, or it really is just a coincidence/convergent evolution. 

Actuation Force: 45g

Bottom Out Force: 50g

Actuation: 1.5mm

Bottom Out: 3.2mm