looking for barrel shroud/heat shield for Mossberg 500a

I’m looking to pick up a barrel shroud/heat shield for my Mossberg 500a with GRS. I see that some are made from Zytel, while others are metal. Which would be recommended? Where should I purchase it from?

Edit for clarification. My Mossberg 500A has Mossberg’s GRS already on it. I’m just looking for the barrel shroud/heat shield. After doing some research, it looks like I’m going to go with the metal heat shield from Mossberg.