The present invention relates to a heat sealable member comprising a sheet of heat sealable material to a multiwell plate, wherein the sheet is mounted in a frame, and wherein said frame is sized to fit over a multiwell plate so that the sheet is contacted with at least one of the rims of the top of the plate and the individual wells; as well as to the use of the heat sealable member with automatic plate handling apparatus, especially in PCR processes. The present invention further relates to a method for sealing multiwell plates.