<div class="field">
  <% field_name = "#{param_prefix}[preferred_group_size]" %>
  <%= label_tag field_name, t('spree.group_size') %>
  <%= number_field_tag field_name, promotion_action.preferred_group_size, class: "fullwidth", min: 1 %>
</div>

<%= render "spree/admin/promotions/actions/promotion_calculators_with_custom_fields",
  calculators: promotion_action.available_calculators,
  promotion_action: promotion_action,
  param_prefix: param_prefix %>
