tracks/app/views/preferences/_profile.html.erb

<div class="form-group">
  <%= pref_with_text_field 'user', 'first_name' %>
</div>
<div class="form-group">
  <%= pref_with_text_field 'user', 'last_name' %>
</div>
<div class="form-group">
  <%= pref_with_select_field('prefs', 'locale', I18n.available_locales.map {|l| l.to_s}) %>
</div>