Yeah...hardness is actually called "durometer", so 17/90 would be 17mm 90 durometer...the wite ones are usually 90's, the black "buna" ones are usually 70's
serious lack of street cred there skeet. I can see you going into some dingy unit, in an out of the way industrial estate, and asking for an 019 buna, 70 durometer.
The reply would be "yes you can have a couple of those o-rings, but we have a minimum order value of £10. So that will be £10", chuckle, chuckle.
what kindof loctite would i use to seal a small leak on my bottles fill nipple, around the thread? seeeing as skeet and tom allen are so knowledgeable i thought i may as well post it in here rather than start a new thread.