Rail mounted iron sights.
The item id for Colonizer Iron Sights in unturned is 5034. You can use this ID with the commands below to spawn the item, give it to a player or buy it on a modded economy server.
Size_X: 1
Size_Y: 1
Size_Z: 0.05
Blueprints: 1
Blueprint_0_Type: Tool
Blueprint_0_Supplies: 1
Blueprint_0_Supply_0_ID: 5034
Blueprint_0_Product: 67
Blueprint_0_Products: 1
Blueprint_0_Build: 27