diff --git a/gems/concurrent-ruby/1.1/_test/test_helpers.rbs b/gems/concurrent-ruby/1.1/_test/test_helpers.rbs
new file mode 100644
index 000000000..77791e7bf
--- /dev/null
+++ b/gems/concurrent-ruby/1.1/_test/test_helpers.rbs
@@ -0,0 +1,3 @@
+class TaskObserver
+  include Concurrent::_Observer[untyped]
+end
diff --git a/gems/concurrent-ruby/1.1/_test/timer_task.rb b/gems/concurrent-ruby/1.1/_test/timer_task.rb
new file mode 100644
index 000000000..1df48c06f
--- /dev/null
+++ b/gems/concurrent-ruby/1.1/_test/timer_task.rb
@@ -0,0 +1,65 @@
+require 'concurrent-ruby'
+
+# Basic usage
+task = Concurrent::TimerTask.new{ puts 'Boom!' }
+task.execute
+task.execution_interval #=> 60 (default)
+task.shutdown #=> true
+
+
+# Configuring :execution_interval
+task = Concurrent::TimerTask.new(execution_interval: 5) do
+  puts 'Boom!'
+end
+task.execution_interval #=> 5
+
+# Immediate execution with :run_now
+task = Concurrent::TimerTask.new(run_now: true) { puts 'Boom!' }
+task.execute
+
+# Configuring :interval_type with either :fixed_delay or :fixed_rate, default is :fixed_delay
+
+task = Concurrent::TimerTask.new(execution_interval: 5, interval_type: :fixed_rate) do
+  puts 'Boom!'
+end
+task.interval_type #=> :fixed_rate
+
+# Last #value and Dereferenceable mixin
+task = Concurrent::TimerTask.new(
+  dup_on_deref: true,
+  execution_interval: 5
+){ Time.now }
+task.execute
+task.value
+
+# Controlling execution from within the block
+timer_task = Concurrent::TimerTask.new(execution_interval: 1) do |task|
+  task.execution_interval.to_i.times { print 'Boom! ' }
+  task.execution_interval += 1
+  if task.execution_interval > 5
+    puts 'Stopping...'
+    task.shutdown
+  end
+end
+
+timer_task.execute
+
+# Observation
+
+class TaskObserver
+  def update(time, result, ex)
+    if result
+      print "(#{time}) Execution successfully returned #{result}\n"
+    else
+      print "(#{time}) Execution failed with error #{ex}\n"
+    end
+  end
+end
+
+task = Concurrent::TimerTask.new(execution_interval: 1){ 42 }
+task.add_observer(TaskObserver.new)
+task.add_observer { |time, result, error| pp time, result, error }
+task.add_observer { |time, result| pp time, result }
+task.add_observer { |time| pp time }
+task.execute
+task.shutdown
diff --git a/gems/concurrent-ruby/1.1/timer_task.rbs b/gems/concurrent-ruby/1.1/timer_task.rbs
new file mode 100644
index 000000000..334fb9257
--- /dev/null
+++ b/gems/concurrent-ruby/1.1/timer_task.rbs
@@ -0,0 +1,47 @@
+module Concurrent
+  interface _Observer[T]
+    def update: (Time, T? result, StandardError? exception) -> void
+  end
+
+  interface _Dereferenceable[T]
+    def value: -> T
+    def deref: -> T
+  end
+
+  interface _Observable[T]
+    def add_observer: (_Observer[T]) -> _Observer[T] #  Typed: observer with standard `update` method
+                    | () { (?Time, ?T?, ?StandardError?) -> void } -> ^(?Time, ?T?, ?StandardError?) -> void # Typed: block form
+                    | (untyped observer, Symbol func) -> untyped # Untyped: custom method name
+    def count_observers: -> Integer
+    def delete_observer: (_Observer[T]) -> _Observer[T]
+                       | (^(?Time, ?T?, ?StandardError?) -> void) -> ^(?Time, ?T?, ?StandardError?) -> void
+                       | (untyped observer) -> untyped
+    def delete_observers: -> self
+    def with_observer: (_Observer[T]) -> self
+                     | () { (?Time, ?T?, ?StandardError?) -> void } -> self
+                     | (untyped observer, Symbol func) -> self
+  end
+
+  class TimerTask[T]
+    include _Observable[T]
+    include _Dereferenceable[T]
+
+    def initialize: (
+      ?execution_interval: Float | Integer,
+      ?run_now: bool,
+      ?executor: executor,
+      ?dup_on_deref: bool,
+      ?freeze_on_deref: bool,
+      ?copy_on_deref: (^(T) -> T)?,
+      ?interval_type: :fixed_rate | :fixed_delay
+    ) { (instance) -> T } -> void
+
+    def execute: -> self
+    def execution_interval: -> (Float | Integer)
+    def execution_interval=: (Float | Integer) -> void
+    def shutdown: -> bool
+    def interval_type: -> (:fixed_rate | :fixed_delay)
+    def timeout_interval: -> Float
+    def running?: -> bool
+  end
+end