The invention relates to a valve which is insertable into a receiving recess (21) of a valve carrier (22), the valve (1, 1′) comprising a first housing part (2, 2′) and a closing body (4). The closing body (4) cooperates with a sealing surface (9) to form a sealing seat, the valve (1, 1′) being fixable in the receiving recess (21) of the valve carrier (22) by means of the first housing part (2, 2′). A second housing part (3, 3′) is connectable by way of a first end (7) to the first housing part (2, 2′) and the sealing surface (9) cooperating with the closing body (4) is formed on the second housing part (3, 3′).