#32 on the parts listing but doesn't show up on the page A1 diagram. Version 1 This is the bumper on the front of the bolt if you have a white or bronze colored bolt. This is no longer the suggested part. Version 2 If you need to replace this bumper on your white or bronze bolt you should use a ORN01090UR oring instead of the bumper. It's a tight fit and you have to stretch it over, but it will go. If you already have 2 Orings on your bolt and no bumper then we're referring to the front of the 2 orings at this point. Version 3 If you have a silver bolt then instead of the original bumper or ORN01090UR oring you should use a ORN01590UR oring.