Piston o-ring for:Gilson Pipetman Classic 1000μL (P1000)Rainin Classic 1000μL (PR1000)Gilson Pipetman Fixed F250, F300, F400, F500, F1000Gilson Pipetman Neo 1000μL (P1000N)Alternative to Gilson F161809, F144498, Rainin 400003, 17003385, 17003458.With 91000, alternative to Gilson set F144866.Made in the USA