diff --git a/sb3_trl/trl_pg/trl_pg.py b/sb3_trl/trl_pg/trl_pg.py
index 37d86b2..ef1b62c 100644
--- a/sb3_trl/trl_pg/trl_pg.py
+++ b/sb3_trl/trl_pg/trl_pg.py
@@ -15,6 +15,9 @@ from stable_baselines3.common.buffers import RolloutBuffer
 from stable_baselines3.common.callbacks import BaseCallback
 from stable_baselines3.common.utils import obs_as_tensor
 
+from ..projections.base_projection_layer import BaseProjectionLayer
+from ..projections.frob_projection_layer import FrobeniusProjectionLayer
+
 
 class TRL_PG(OnPolicyAlgorithm):
     """
@@ -63,9 +66,9 @@ class TRL_PG(OnPolicyAlgorithm):
     :param seed: Seed for the pseudo random generators
     :param device: Device (cpu, cuda, ...) on which the code should be run.
         Setting it to auto, the code will be run on the GPU if possible.
+    :param projection: What kind of Projection to use
     :param _init_setup_model: Whether or not to build the network at the creation of the instance
     """
-    # TODO: Add new params to doc
 
     policy_aliases: Dict[str, Type[BasePolicy]] = {
         "MlpPolicy": ActorCriticPolicy,
@@ -100,8 +103,7 @@ class TRL_PG(OnPolicyAlgorithm):
         device: Union[th.device, str] = "auto",
 
         # Different from PPO:
-        #projection: BaseProjectionLayer = None,
-        projection=None,
+        projection: BaseProjectionLayer = BaseProjectionLayer,
 
         _init_setup_model: bool = True,
     ):
@@ -300,9 +302,9 @@ class TRL_PG(OnPolicyAlgorithm):
                 entropy_losses.append(entropy_loss.item())
 
                 # Difference to PPO: Added trust_region_loss; policy_loss includes entropy_loss + trust_region_loss
-                # trust_region_loss = self.projection.get_trust_region_loss()#TODO: params
-                trust_region_loss = th.zeros(
-                    1, device=entropy_loss.device)  # TODO: Implement
+                trust_region_loss = self.projection.get_trust_region_loss(
+                    pol, p, proj_p)
+                # NOTE to future-self: policy has a different interface then in orig TRL-impl.
 
                 trust_region_losses.append(trust_region_loss.item())
 
@@ -471,7 +473,7 @@ class TRL_PG(OnPolicyAlgorithm):
                             0]
                     rewards[idx] += self.gamma * terminal_value
 
-            # TODO: calc mean + std
+            # TODO: how to calc mean + std
             rollout_buffer.add(self._last_obs, actions, rewards,
                                self._last_episode_starts, values, log_probs, mean, std)
             self._last_obs = new_obs