The S1 and S2 design with standardised ground joint (vacuum-proof, unpressurised) Magnetic stirrer couplings with NS 29/32 (S1) or NS 45/40 (S2) joint are specially designed for use in flasks and glass reactors with ground joint connections. The encapsulated inner magnet couples to the external drive magnet bell and provides the drive force. This process involves absolutely gas-tight stirring. The sealing takes place via O-rings on the conical part and is made of FKM as standard. Alternatively, these can also be equipped in FFKM of various qualities on request.