These are nickel plated steel key holders; each has 4 rings to hold keys, but each ring looks like it can hold 2-3-4 keys.  It can be as jingly-jangly as you want it to be, we guess.  Attaches to your project with two rivets which are NOT included.  Sold in packs of ten for $18.00 flat, USA shipping included.  Part number RNG-126