diff --git a/lib/ably/models/delta_extras.rb b/lib/ably/models/delta_extras.rb
new file mode 100644
index 000000000..8a9c35538
--- /dev/null
+++ b/lib/ably/models/delta_extras.rb
@@ -0,0 +1,29 @@
+module Ably::Models
+  #
+  # @!attribute [r] from
+  #   @return [String] The id of the message the delta was generated from
+  # @!attribute [r] format
+  #   @return [String] The delta format. Only vcdiff is supported as at API version 1.2
+  #
+  class DeltaExtras
+    include Ably::Modules::ModelCommon
+
+    # The id of the message the delta was generated from.
+    # @return [String, nil]
+    #
+    attr_reader :from
+
+    # The delta format.
+    # @return [String, nil]
+    #
+    attr_reader :format
+
+    def initialize(attributes = {})
+      @from, @format = IdiomaticRubyWrapper((attributes || {}), stop_at: [:from, :format]).attributes.values_at(:from, :format)
+    end
+
+    def to_json(*args)
+      as_json(args).to_json
+    end
+  end
+end
diff --git a/lib/ably/models/message.rb b/lib/ably/models/message.rb
index a8eb89e12..c1b3e0eec 100644
--- a/lib/ably/models/message.rb
+++ b/lib/ably/models/message.rb
@@ -142,6 +142,9 @@ def protocol_message
 
     # Contains any arbitrary key value pairs which may also contain other primitive JSON types, JSON-encodable objects or JSON-encodable arrays.
     # The extras field is provided to contain message metadata and/or ancillary payloads in support of specific functionality, e.g. push
+    # 1.2 adds the delta extension which is of type DeltaExtras, and the headers extension, which contains arbitrary string->string key-value pairs,
+    # settable at publish time. Unless otherwise specified, the client library should not attempt to do any filtering or validation of the extras
+    # field itself, but should treat it opaquely, encoding it and passing it to realtime unaltered.
     # @api private
     def extras
       attributes[:extras].tap do |val|
@@ -151,6 +154,14 @@ def extras
       end
     end
 
+    # Delta extras extension (TM2i)
+    # @return [DeltaExtras, nil]
+    # @api private
+    def delta_extras
+      return nil if attributes[:extras][:delta].nil?
+      @delta_extras ||= DeltaExtras.new(attributes[:extras][:delta]).freeze
+    end
+
     private
     def raw_hash_object
       @raw_hash_object
diff --git a/spec/unit/models/delta_extras_spec.rb b/spec/unit/models/delta_extras_spec.rb
new file mode 100644
index 000000000..4b7da7ed5
--- /dev/null
+++ b/spec/unit/models/delta_extras_spec.rb
@@ -0,0 +1,14 @@
+# encoding: utf-8
+require 'spec_helper'
+
+describe Ably::Models::DeltaExtras do
+  subject { described_class.new({ format: 'vcdiff', from: '1234-4567-8910-1001-1111'}) }
+
+  it 'should have `from` attribute' do
+    expect(subject.from).to eq('1234-4567-8910-1001-1111')
+  end
+
+  it 'should have `format` attribute' do
+    expect(subject.format).to eq('vcdiff')
+  end
+end
diff --git a/spec/unit/models/message_spec.rb b/spec/unit/models/message_spec.rb
index fd51005d5..fd5444ae9 100644
--- a/spec/unit/models/message_spec.rb
+++ b/spec/unit/models/message_spec.rb
@@ -606,4 +606,28 @@
       end
     end
   end
+
+  context '#delta_extras (TM2i)' do
+    let(:delta_extras) { message.delta_extras }
+
+    context 'when delta' do
+      let(:message) { subject.new({ extras: { delta: { from: '1234-1234-5678-9009', format: 'vcdiff' } } }) }
+
+      it 'should return vcdiff format' do
+        expect(delta_extras.format).to eq('vcdiff')
+      end
+
+      it 'should return 1234-1234-5678-9009 message id' do
+        expect(delta_extras.from).to eq('1234-1234-5678-9009')
+      end
+    end
+
+    context 'when no delta' do
+      let(:message) { subject.new({ extras: {} }) }
+
+      it 'should return nil' do
+        expect(delta_extras).to eq(nil)
+      end
+    end
+  end
 end