$(document).ready(function() {
  setInterval('slideshow();', 5000);
});

function slideshow() {
  var currentModel = $('#model-image .visible').attr('id');
  var id = currentModel.substring(12);
  $('#'+currentModel).removeClass('visible');
  $('#'+currentModel).fadeOut(900);
  id++;
  if (id > 2) {
    id = 1;
  }
  $('#model-image-'+id).fadeIn(900);
  $('#model-image-'+id).addClass('visible');
}