The Sicomatic T-plus lid does not automatically fit an old Sicomatic L, as models and lid sizes may vary. It is essential to check compatibility according to the exact specifications of each model, in particular the diameter of the lid. For a Sicomatic T-plus, the Ø22 cm lid is generally used, but you need to make sure that this diameter matches that of the old Sicomatic L. If you have any doubts, it's best to consult the technical documents or contact the manufacturer for confirmation.