These are solid and hold tight if you find a pair with the rubber in tact. They can be pricey but great option if you want vintage clamps that perform.
Solid attachment that is good for curling or push down moves. Knurling is good, not passive but does not eat at your hands. This was free when REP gave points.
Questionable knurling but my wife loves them. I have 2.5lb jumps 2.5 to 30 lbs. free shipping and on sale often. These are all out of the same factory. Many times sales are cheaper than used.