Here is vintage trap style jigger that has no maker’s marks. I believe it is chrome plated. It has nice weight to it. The handle measures about 4 inches long and the cup is 1 and 3/4 inches in diameter and about 2 inches tall. The round yellowish ball handles have a bakelite appearance but could be some type of plastic or resin.
To use this jigger, hold it over your glass or cup, pour in the liquid, place the handles across the cup to rest on the edge and lightly push down to release the liquid.
I have seen Fay trap jiggers with red bakelite knobs but never one such as this with yellow knobs.
This jigger is available for sale here at my Etsy shop: https://www.etsy.com/listing/627880718/vintage-trap-jigger-yellow-knobs