I own two Hatsan PCP air rifles and know the importance of quality O-rings for the fill probe first hand. After doing testing, I am now using these black O-rings that are made from Buna-N rubber that is oil resistant and tolerates the silicone grease we use to lubricate the fill probes just fine. To get a good seal, their durometer, or hardess, is 70A, which is ideal for high pressure air.
These O-rings should fit fill probes from the following companies (and model if they have more than one size of probe like Air Venturi and Hammerli do):
- Air Venturi Halestorm
- Hammerli Pneuma
These are sold in packages of 4 O-rings. If you order two packages then that means you will get 8 O-rings and so on.
This listing is just for the O-rings. Any photos of fill probes are for comparison purposes