a basketful of elderly electrical wiring insulators

These are all various sorts of ceramic insulators which were used with what's called "knob and tube" wiring in an original 1920's home electrical installation. A style/method of doing so in the initial eras of home electrification, such wiring is generally considered hazardous where it remains in use these days, often for good reason if it hasn't remained completely hidden and undisturbed since then, at least. The "tubes" are the various long narrow things, used where the individual wire conductors passed through wall studs and ceiling rafters -- the "knobs" are the shorter fatter things (several different types, all common) with the nails used where wires were strung alongside or across studs and rafters. There are also a couple assorted 2-pc cable clamps in the mix. ALL these were intended to keep those various single conductor (usually all black in color) wires held in place securely ('safely' they said then, and it truly would have been better when the wire was still fresh and pliable) and away from potential damage.

This little basketful was actually recovered mostly from one old house which I did a lot of work on years ago, but I know I have plenty more similar (and not) kinds of antique ceramic wiring bits and pieces too, those are scattered all around the place in boxes and drawers etc -- this bunch is likely my single largest 'recovery stash'... <lol>