Dow #111. A 5.3 oz tube (lifetime supply?) was $11.35 at McMaster. Their # 1204K32. I also use it on all my Moen faucet valves at home, but be careful - get them too slippery and the weight of the handle will close the valve. Some O-rings don't react kindly to petroleum lubricants - causes them to swell (and who knows what else). O-rings are made from a wide variety of elastomers - which I can't tell apart. And identification tests seem to be destructive - burn them and smell the smoke??? Like my wife's father's test for a good piece of antique furniture - burns with a clear blue flame.