A heating or atomising unit for an electronic cigarette vaporiser, in which the unit includes a protective elastomer wall or barrier configured to enable (i) the unit to fit inside a body in the vaporizer and to prevent leakage around the outside of the unit whilst e-liquid is being supplied under pressure to a reservoir surrounding the unit and (ii) e-liquid to pass from the e-liquid reservoir outside of the unit and into the unit. The unit can be a cylindrical ceramic cell and the elastomer wall can be a pair of silicone end-caps placed on each end of the cylinder, separated by a gap through which e-liquid can reach the outer surface of the ceramic cell and pass through the ceramic and into the atomizing chamber in the cell.