Just received Sorties breech seals from HatsanUSA. They appear to be black o-rings. Picture attached. My measurements for the 0.25 are 9 mm OD, 7 mm ID with 1 mm thickness. For the 0.22 I find 8 mm OD, 6 mm ID with 1 mm thickness. My Sorties appear to have a groove at the breech which I assume these seals fit in. 