app/views/spree/admin/products/_product_assembly_fields.html.erb
<div data-hook="admin_product_form_can_be_part">
<%= f.field_container :can_be_part, class: ['form-group'] do %>
<%= f.label :can_be_part %>
<%= f.error_message_on :can_be_part %>
<%= f.check_box :can_be_part, class: 'form-control' %>
<% end %>
</div>
<div data-hook="admin_product_form_individual_sale">
<%= f.field_container :individual_sale, class: ['form-group'] do %>
<%= f.label :individual_sale %>
<%= f.error_message_on :individual_sale %>
<%= f.check_box :individual_sale, class: 'form-control' %>
<% end %>
</div>
<% if @product.assembly? %>
<% content_for :head do %>
<script type="text/javascript">
jQuery(document).ready(function(){
$("input[id='product_on_hand']").attr('disabled',true).parent().hide();
$("input#product_can_be_part").attr('disabled',true);
});
</script>
<% end %>
<% end %>