Abstract: The invention relates to a covering device (10), in particular a lid, for covering reaction vessels (50), in particular PCR plates, microtiter plates, and the like, comprising: a substantially flat main body (14) having an inside (34) and an outside (12), at least one planar sealing element (36) arranged on the main body (14) and connected to the main body, wherein the at least one sealing element (36) is arranged on the inside (34) of the main body (14), an edge segment (16), which runs along the periphery of the main body and extends from the outside (12) in the direction of the inside (34) and beyond the inside, and at least one spring element (22, 24) arranged on the main body (14) or on the sealing element (36), which at least one spring element is designed in such a way that the at least one spring element supports the covering device (10) on a surface (54) of a reaction vessel (50) to be covered facing the covering device (10) in the relaxed state of the at least one spring element and that an intermed