You can buy them on Amazon for less than $20.
https://www.amazon.com/Royal-Enfield-Meteor-Filter-Rings/dp/B09W1W4YGG/ref=sr\_1\_5?gclid=Cj0KCQjwgMqSBhDCARIsAIIVN1VFqBnw57rRkt69mr5T1vt0qkarA0wwnRBuHrSoyhTp7T3TePxhWm8aAiMKEALw\_wcB&hvadid=535936663599&hvdev=c&hvlocphy=9028249&hvnetw=g&hvqmt=b&hvrand=8731958852484375981&hvtargid=kwd-325571121264&hydadcr=7660\_9903400&keywords=royal+enfield+oil+filter+kit&qid=1649640990&sr=8-5