A medium temperature smoke door bottom seal, with an extruded silicon sealing component. It is as heavy duty automatic door bottom seal which is spring loaded to lift clear of the floor as soon as the door leaf is opened by a few millimetres. The seal is operated automatically by pressure against the door jamb on the adjusting screw. It seals when the door closes and retracts automatically when the door is opened. It is seld levelling. RP38 Si can be face mounted or semi morticed in proprietary fire doors. It is adjustable for left and rigth handed operation. When semi morticing RP38Si into double doors that require rebated meeting stiles, specify 40mm minimum thickness.