diff --git a/app/search_builders/hyrax/catalog_search_builder.rb b/app/search_builders/hyrax/catalog_search_builder.rb
index <HASH>..<HASH> 100644
--- a/app/search_builders/hyrax/catalog_search_builder.rb
+++ b/app/search_builders/hyrax/catalog_search_builder.rb
@@ -1,3 +1,31 @@
+##
+# The default Blacklight catalog `search_builder_class` for Hyrax.
+#
+# Use of this builder is configured in the `CatalogController` generated by
+# Hyrax's install task.
+#
+# If you plan to customize the base catalog search builder behavior (e.g. by
+# adding a mixin module provided by a blacklight extension gem), inheriting this
+#  class, customizing behavior, and reconfiguring `CatalogController` is the
+# preferred mechanism.
+#
+# @example extending and customizing SearchBuilder
+#   class MyApp::CustomCatalogSearchBuilder < Hyrax::CatalogSearchBuilder
+#     include BlacklightRangeLimit::RangeLimitBuilder
+#     # and/or other extensions
+#   end
+#
+#   class CatalogController < ApplicationController
+#     # ...
+#     configure_blacklight do |config|
+#       config.search_builder_class = MyApp::CustomCatalogSearchBuilder
+#     # ...
+#     end
+#     # ...
+#   end
+#
+# @see Blacklight::SearchBuilder
+# @see Hyrax::SearchFilters
 class Hyrax::CatalogSearchBuilder < Hyrax::SearchBuilder
   self.default_processor_chain += [
     :add_access_controls_to_solr_params,
Add class level documentation for `Hyrax::CatalogSearchBuilder`

Some folks were thinking about ways to extend this class, but had missed that
Blacklight provides an extension mechanism. Adding some class level docs should
help folks find the right extension points.