{% load wagtailcore_tags wagtailimages_tags %}
<div class="image-grid-block">
    {% for img in self.images %}
        <div class="image-grid-item" style="display: inline-block; width: {{ self.image_width|default:300 }}px; vertical-align: top;">
            {% image img original %}
        </div>
    {% endfor %}
</div>