$(document).ready(function(){
var size = $('.model-list-block').find('li').length();
$('.model-list-all').hide();
if (size > 20) {
$('.model-list-block').find('li').slice(20, size).hide();
$('.model-list-all').show();
}
$('.model-list-all').on('click', function () {
$('.model-list-block').find('li').slice(20, size).show();
$(this).hide();
});
)}