These are the main tuning and bandspread knobs for a late-1950's to middle-1960's version boatanchor receiver. Looking at pictures of old National Radio receivers, these knobs appear to match the NC-173, NC-183, NC-140, and/or NC-400 receivers. The shadow on the chrome flashing on one knob is an artifact of photography. The circular mirror picked up a corner of my hand when I was taking the picture. I just noticed that the larger gray knob is missing one of its two Allen screws. I'll include a replacement screw if I can find one in my junk box, but no guarantees. In any case, they're readily available at your local Ace Hardware store.
I bought these at a hamfest years ago and never used them for the project I was building. I found them a few days ago when I was looking for something else. So I decided that it's now time for them to find a new owner, instead of taking up space over here. $18 postpaid to anywhere in the USA.