A window or door comprising: a frame, a sliding panel housed within the frame and comprising a first edge, wherein the sliding panel is slideable between a closed position and an open position to define an opening adjacent the first edge; a roller assembly comprising: a screen attached to the first edge of the sliding panel; a spindle around which the screen is wound and rotatably mounted adjacent the first edge when the sliding panel is in the closed position so that the screen can be unwound from the spindle as the sliding panel is opened, and wound back onto the spindle as the sliding panel is closing; and a spindle rotation assembly for rotating the spindle; an idler pulley located within the frame; at least one operative means connected between the sliding panel and the spindle rotation assembly via the idler pulley, that causes the spindle to rotate so as to wind the screen back onto the spindle as the sliding panel is closing; characterised in that the window or door further comprises: a tension adjustment arrangement comprising a mount housing that houses the idler pulley, a spring anchor securable with respect to the frame, and a spring secured between the mount housing and the spring anchor wherein the tension adjustment arrangement is configured to adjust the tension in the operative means as the screen is wound and unwound from the spindle, wherein the frame comprises an upper slot, and the tension adjustment arrangement is located and secured in the upper slot, and the upper slot comprises two side walls and the spring anchor is a block with tapered sides, and the tension adjustment arrangement further comprises a U shaped receiving block that is fastened to the spring anchor so that the tapered sides of the spring anchor force the walls of the a U shaped receiving block outwards to generate an interference fit with the two side walls of the upper slot to secure the spring anchor in the upper slot. a frame, a sliding panel housed within the frame and comprising a first edge, wherein the sliding panel is slideable between a closed position and an open position to define an opening adjacent the first edge; a roller assembly comprising: a screen attached to the first edge of the sliding panel; a spindle around which the screen is wound and rotatably mounted adjacent the first edge when the sliding panel is in the closed position so that the screen can be unwound from the spindle as the sliding panel is opened, and wound back onto the spindle as the sliding panel is closing; and a spindle rotation assembly for rotating the spindle; a screen attached to the first edge of the sliding panel; a spindle around which the screen is wound and rotatably mounted adjacent the first edge when the sliding panel is in the closed position so that the screen can be unwound from the spindle as the sliding panel is opened, and wound back onto the spindle as the sliding panel is closing; and a spindle rotation assembly for rotating the spindle; an idler pulley located within the frame; at least one operative means connected between the sliding panel and the spindle rotation assembly via the idler pulley, that causes the spindle to rotate so as to wind the screen back onto the spindle as the sliding panel is closing; characterised in that the window or door further comprises: a tension adjustment arrangement comprising a mount housing that houses the idler pulley, a spring anchor securable with respect to the frame, and a spring secured between the mount housing and the spring anchor wherein the tension adjustment arrangement is configured to adjust the tension in the operative means as the screen is wound and unwound from the spindle, wherein the frame comprises an upper slot, and the tension adjustment arrangement is located and secured in the upper slot, and the upper slot comprises two side walls and the spring anchor is a block with tapered sides, and the tension adjustment arrangement further comprises a U shaped receiving block that is fastened to the spring anchor so that the tapered sides of the spring anchor force the walls of the a U shaped receiving block outwards to generate an interference fit with the two side walls of the upper slot to secure the spring anchor in the upper slot. a tension adjustment arrangement comprising a mount housing that houses the idler pulley, a spring anchor securable with respect to the frame, and a spring secured between the mount housing and the spring anchor wherein the tension adjustment arrangement is configured to adjust the tension in the operative means as the screen is wound and unwound from the spindle, wherein the frame comprises an upper slot, and the tension adjustment arrangement is located and secured in the upper slot, and the upper slot comprises two side walls and the spring anchor is a block with tapered sides, and the tension adjustment arrangement further comprises a U shaped receiving block that is fastened to the spring anchor so that the tapered sides of the spring anchor force the walls of the a U shaped receiving block outwards to generate an interference fit with the two side walls of the upper slot to secure the spring anchor in the upper slot.