function sendRequestSearch(merk_id,type_id)
{
  if (merk_id>0)
  {
    if(window.XMLHttpRequest) xmlhttp = new XMLHttpRequest();
    else if(window.ActiveXObject) xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
    xmlhttp.onreadystatechange= function() { 
        if (xmlhttp.readyState==4)
            if (xmlhttp.status==200)
                Showit(xmlhttp,merk_id);
    }
    
    xmlhttp.open('GET','require/get_models.php?merk_id='+merk_id+'&type_id='+type_id,true);
    xmlhttp.send(null);
  }
}

function Showit(req,field) {
    document.getElementById('modeltype_box1').style.display = 'none';
    document.getElementById('modeltype_box2').innerHTML = req.responseText;  
}