V90113 Halkey Roberts Manifold O Ring.
The V90113 Halkey Roberts O Ring can be bought individually or in a Multi Pack which you can find on this link.
It is used mainly on the Halkey Roberts V90000 Alpha Inflators as the manifold seal/gasket.
This O Ring is fitted 2 per device. It sits on top and under the inflator head. Anyone checking and fitting this part needs to have good technical knowledge of the product. This is typically a trade part used by lifejacket service stations and larger commercial users who have internal servicing.
More information can be found here on the manufacturers website.