product-template.liquid

 {% form 'product', product, class:form_classes, novalidate: 'novalidate', data-product-form: '' %}
            {% unless product.has_only_default_variant %}
              <div class="product-form__controls-group">
                {% for option in product.options_with_values %}
                <div class="selector-wrapper js product-form__item">
                      <p>{{ option.name }}</p>
                        {% if option.name == "Size" %}
                          {% assign index = forloop.index %}
                          <div class="size-selector">
                            <div class="size-selector__list">
                              {% for value in option.values %}
                              {% assign sizeWords = value | split: ' ' %}
                              {% capture sizeLetters %}{% for word in sizeWords %}
                              {{ word | slice: 0 }}
                              {% endfor %}{% endcapture %}
                              <div class="size-selector__item">
                                <input 
                                 class="single-option-selector-{{ section.id }}" 
                                 id="size-{{ forloop.index }}" type="radio" name="size" 
                                 value="{{ value | escape }}" 
                                 data-index="option{{index}}"
                                 {% if option.selected_value == value %} checked="true"{% endif %} />
                                <label for="size-{{ forloop.index }}">{{ sizeLetters }}</label>
                              </div>
                              {% endfor %}
                            </div>
                          </div>
                      {% else %}
                      
               		 </div>
                    <label for="SingleOptionSelector-{{ forloop.index0 }}">
                      {{ option.name }}
                    </label>
                    <select class="single-option-selector single-option-selector-{{ section.id }} product-form__input"
                      id="SingleOptionSelector-{{ forloop.index0 }}"
                      data-index="option{{ forloop.index }}"
                    >
                      {% for value in option.values %}
                        <option value="{{ value | escape }}"{% if option.selected_value == value %} selected="selected"{% endif %}>{{ value }}</option>
                      {% endfor %}
                    </select>
                {% endif %}
                  </div>
                {% endfor %}
              </div>
            {% endunless %}