Marklin 60821 - Accessory Set for the m 83 Decoder
This is a turnout motor front end circuit board for the m 83 decoder. It is for using turnout mechanisms with motors with an end shutoff feature in the end stop position. This can only be used in conjunction with the m 83 (60831).
When you are operating such mechanisms with the m 83, you can program the set speed as well as a slow approach to the end position.