Joint size 14/23, this extension kit contains 8 items required to convert 27BU/M to 23BU/M. Consists of 1 Round bottom flask 25 ml 1 Air condenser 1 Sintered glass funnel 1 Drying tube 1 Pear shaped flask 50 ml - 2 neck 1 Steam inlet tube 1 Adaptor with T - connector 1 Screwcap adaptor