preferably an N21 2 piece plug .This was the earlier plug. Could be taken apart and decarbonised etc and re- assebled and re-used virtualy forever. Klg had asimilar plug from memory called FE20. We used to buy alot more KLG as the cam in atin box with hinged lid which were very handy for keeping smaller parts in. Is the N21 plug still in shops for sale??????????????