Genuine OEM Toyota Waterneck Bypass Pipe O-rings.
These o-ring sits on each end of the bypass pipe from the waterneck to the head on all JZ motors. I recommend if you are removing this bypass pipe to always replace these o-rings to prevent coolant leaks.
Note: This product does not come in the OEM Toyota packaging, as Toyota doesn't sell this item usually individually. Photo shows one o-ring but his listing is for a pair as each side of the by-pass pipe requires an o-ring.