As the title says it's a free-flow K&N air filter element (part no 33-2011) that fits the Rover 2200 TC and also 60's and 70's Jaguar XJ6, XJ12, XJS, Triumph Dolomite Sprint, Triumph Stag, Lotus Esprit 2.2 and probably some others that use a similar filter case.
I have used it only for one year...