Optimate branded trickle chargers come with a very diverse range of accessories.
Depending on what you do with it, where you want to do it and whether or not all current and legacy systems are compatible, you'll find everything you need here, from DIN plugs and extension cords to voltage indicators and alligator clips.
The type of connection on your Optimate battery charger is the only thing you really need to consider. Below is an image showing the difference between the older TM and the newer SAE connector. On the left side of this page you can filter for the type of connection you need.