Matched set. Two sizes: 6 larger ones at 2-3/8 inches, 2 smaller ones 1-7/8 inches. They are about 3/4 inch deep.

The backs have a threaded center hole for mounting with a bolt - the threads are good, a standard bolt I had in another knob threaded easily into the 6 larger knobs. The holes on the smaller knobs are a fraction bigger and need a bigger bolt. Bolts are not included. Note there are metal "stick-prongs" on each side of the mounting hole to aid in holding it tight in the wood. The presence of these prongs leads me to believe there were never backplates with them.

They are quite attractive as they are but do have substantial dark patina of the brass. Any cleaning/restoring/polishing is left to the buyer decision. See/study all the photos to complete the description.