Review on Presto Pressure Cooker Sealing Automatic by Kathy Miller

O-ring fits my Presto 4-412 "no spare parts" Super. The vent is free but under pressure. Raised the temperature to a hiss, scary and ready to go. Part 09909 What I measured. Ring outer diameter 9 inches, width 3/8 inches, thickness 7/64 inches. I have to say that it fits perfectly because it is snug. groove and 1/2-3/4 the length to hold it in the groove. You want it to be like this. If you work dry and overheat things, they will shrink in length. Squeeze them as you insert them into the groove (e.g. by pushing a rope uphill) and you can squeeze them 2 inches or more. Idea. when you ran out of water and everything turned black and shrank. mine shrunk maybe an inch and was too small :-(Update. I wrapped it around a slightly larger salad bowl for 3 days and it stretched and didn't shrink..lol :-)