Abstract: The knock-down structure of the filter comprises a body with a cover and a filtering element with a bypass valve and an anti-drain valve, a filtering element of the bypass valve and a spring, arranged coaxially inside the body. The body is provided with an annular groove accommodating a split locking ring. On the external cylindrical surface of the cover at least one annular groove is provided in which a sealing gasket and a projection are disposed, said projection interacting with said split locking ring. The one-piece structure of the filter does not comprise a locking ring and projection, the body having a beading made at the end edge thereof and directed toward the interior of the body, the cover being made likewise with a sealing gasket, the external end surface of the cover interacting with the beading of the body.