A printing screen unit, comprising: a printing screen (12; 42; 62; 82; 112), comprising a sheet of rectangular shape having two pairs of opposite edges; a supporting frame having first and second pairs of interface members (16, 16; 46, 46; 66, 66; 86, 86, 87, 87; 116, 116; 117, 117) attached to each of the pairs of opposite edges of the sheet, wherein the interface members (16, 16; 46, 46; 66, 66; 86, 86, 87, 87; 116, 116; 117, 117) each comprise an elongate member which extends along the length of the respective edge of the sheet, and the interface members (16, 16; 46, 46; 66, 66; 86, 86, 87, 87; 116, 116; 117, 117) each include an attachment section (24; 54; 72; 92; 126) which is attached to a respective edge of the sheet, and an engagement section (24; 58; 74; 94; 140) which includes an engagement surface (28; 59; 78; 142) which is adapted to engage a respective tensioning mechanism, the engagement surface (28; 59; 78; 142) of each interface member (16, 16; 46, 46; 66, 66; 86, 86, 87, 87; 116, 116; 117, 117) being inwardly-facing, inclined outwardly from a free edge of the engagement surface (28; 59; 78; 142) relative to the respective edge of the sheet, and defined by a continuous surface or channel which extends along the length of the respective interface member (16, 16; 46, 46; 66, 66; 86, 86, 87, 87; 116, 116; 117, 117); wherein the printing screen unit is mountable to and demountable from a system for supporting the printing screen unit, and the supporting frame as defined by the interface members (16, 16; 46, 46; 66, 66; 86, 86, 87, 87; 116, 116; 117, 117) confers structural support to the printing screen when the printing screen unit is demounted from the system for supporting the printing screen unit and provides for engagement to tensioning mechanisms when the printing screen unit is mounted to the system for supporting the printing screen unit. a printing screen (12; 42; 62; 82; 112), comprising a sheet of rectangular shape having two pairs of opposite edges; a supporting frame having first and second pairs of interface members (16, 16; 46, 46; 66, 66; 86, 86, 87, 87; 116, 116; 117, 117) attached to each of the pairs of opposite edges of the sheet, wherein the interface members (16, 16; 46, 46; 66, 66; 86, 86, 87, 87; 116, 116; 117, 117) each comprise an elongate member which extends along the length of the respective edge of the sheet, and the interface members (16, 16; 46, 46; 66, 66; 86, 86, 87, 87; 116, 116; 117, 117) each include an attachment section (24; 54; 72; 92; 126) which is attached to a respective edge of the sheet, and an engagement section (24; 58; 74; 94; 140) which includes an engagement surface (28; 59; 78; 142) which is adapted to engage a respective tensioning mechanism, the engagement surface (28; 59; 78; 142) of each interface member (16, 16; 46, 46; 66, 66; 86, 86, 87, 87; 116, 116; 117, 117) being inwardly-facing, inclined outwardly from a free edge of the engagement surface (28; 59; 78; 142) relative to the respective edge of the sheet, and defined by a continuous surface or channel which extends along the length of the respective interface member (16, 16; 46, 46; 66, 66; 86, 86, 87, 87; 116, 116; 117, 117); wherein the printing screen unit is mountable to and demountable from a system for supporting the printing screen unit, and the supporting frame as defined by the interface members (16, 16; 46, 46; 66, 66; 86, 86, 87, 87; 116, 116; 117, 117) confers structural support to the printing screen when the printing screen unit is demounted from the system for supporting the printing screen unit and provides for engagement to tensioning mechanisms when the printing screen unit is mounted to the system for supporting the printing screen unit.