The Viessmann 4018 signal is a model of the small 2 aspect signal typically found in swithing yards. It provides Hp00 and Sh1 aspects and uses LEDs.
They install easily. I was disappointed to find that the Sh1 lights use yellow instead of white LEDs. The catalog shows white lights and I fully expected them to be white as in the prototype. The company is switching to white LEDs in their new signal developments but these will not be retrofitted with white ones.