diff --git a/README.md b/README.md
index 50a9b79..dde0e4e 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1513 TILs and counting..._
+_1514 TILs and counting..._
 
 ---
 
@@ -1040,6 +1040,7 @@ _1513 TILs and counting..._
 - [Update Column Versus Update Attribute](rails/update-column-versus-update-attribute.md)
 - [Upgrading Your Manifest For Sprocket's 4](rails/upgrading-your-manifest-for-sprockets-4.md)
 - [Use IRB And Ruby Flags With Rails Console](rails/use-irb-and-ruby-flags-with-rails-console.md)
+- [Useful ActiveSupport Constants For Durations](rails/useful-active-support-constants-for-durations.md)
 - [Validate Column Data With Check Constraints](rails/validate-column-data-with-check-constraints.md)
 - [Verify And Read A Signed Cookie Value](rails/verify-and-read-a-signed-cookie-value.md)
 - [Where Am I In The Partial Iteration?](rails/where-am-i-in-the-partial-iteration.md)
diff --git a/rails/useful-active-support-constants-for-durations.md b/rails/useful-active-support-constants-for-durations.md
new file mode 100644
index 0000000..461e7e4
--- /dev/null
+++ b/rails/useful-active-support-constants-for-durations.md
@@ -0,0 +1,45 @@
+# Useful ActiveSupport Constants For Durations
+
+Whenever I'm passing a duration to a function, I like to [name it with the
+unit](https://ruudvanasseldonk.com/2022/03/20/please-put-units-in-names)
+relative to the value it represents. For instance, if I need to pass in an hour
+duration in seconds, I might write the following line:
+
+```ruby
+hour_in_seconds = 60 * 60
+
+# or
+
+hour_in_seconds = 3600
+```
+
+ActiveSupport has a [Duration
+class](https://api.rubyonrails.org/classes/ActiveSupport/Duration.html) with a
+series of constants that we can reach for.
+
+```ruby
+> ActiveSupport::Duration::SECONDS_PER_MINUTE
+=> 60
+> ActiveSupport::Duration::SECONDS_PER_HOUR
+=> 3600
+> ActiveSupport::Duration::SECONDS_PER_DAY
+=> 86400
+> ActiveSupport::Duration::SECONDS_PER_WEEK
+=> 604800
+> ActiveSupport::Duration::SECONDS_PER_MONTH
+=> 2629746
+> ActiveSupport::Duration::SECONDS_PER_YEAR
+=> 31556952
+```
+
+Though it is fun to know about these, we should keep in mind that this class
+provides support for what is likely to be a more useful abstraction layer:
+
+```ruby
+> 1.hour
+=> 1 hour
+> 3.hours
+=> 3 hours
+> 1.day.to_i
+=> 86400
+```