Dear Customer,
The inner and outer Oring for OD12mm enhance fitting is BP-ML-O10-BK.
You can find it here. And BP-WTP-O10-BK is the Oring for G1/4"thread.
Any questions, feel free to contact us.
https://shop.bitspower.com/index.php?route=product/product&product_id=356&search=BP-ML-O10
https://shop.bitspower.com/index.php?route=product/product&path=59_128_137&product_id=404