Does anyone know whether Theoben Vortex silencer end caps (the cone shaped version) are interchangeable with Impact Airguns RM100 silencer end caps (also cone shaped)?

Assuming they are interchangeable, the Impact website is advertising the Vortex end caps, but although I've attempted to make contact via email, Messenger and phone I've received no response. I understood Impact remained trading for servicing and spares and their Facebook page appears active. Does anyone know if they're still trading and if so how to make contact?

Thanks.