This is the safety valve rubber for the lid of Asahi Kasei's pressure cooker "Katsuryoku Nabe (SW type)". The included (built-in) part is the seal ball. This is a consumable part taken from an SW 5.5L pot made in 2007. There are no noticeable scratches. This is a common part for the SW type 5.5L and 3.0L sizes. It has a different shape from the current mainstream ZK type and cannot be used interchangeably. #mmkz41's list of Katsuryoku Nabe parts for sale