function sizeChart(chart) {

    var popupWin = null;
    var relIndex = 'popup|900|700|0|1';

    var scrW     = screen.availWidth;
    var scrH     = screen.availHeight; 

    var relSplit = relIndex.split("|");
    
    var windowAttributes = '';

    if (relSplit[1] > scrW) {pW = scrW - 10;}
    else                    {pW = relSplit[1];}

    if (relSplit[2] > scrH) {pH = scrH - 40;}
    else                    {pH = relSplit[2];}

    scrX = (scrW - pW - 10) * .5;
    scrY = (scrH - pH - 30) * .5;

    var windowAttributes  = "width=" + pW + ",height=" + pH + ",left=" + scrX + ",top=" + scrY + ",screenX=" + scrX + ",screenY=" + scrY;

    windowAttributes += ",location=" + relSplit[4] + ",resizable=" + relSplit[4] + ",scrollbars=" + relSplit[4];

    popupWin = window.open('http://www.leg-care.co.uk/store/skins/CUSTOM/charts/size_chart_' + chart + '.htm', 'winPopup', windowAttributes);

}