I assume you mean the power connection to the track.
If your layout is going to be DC Analogue controlled, then you need either the R8206 power track OR the R602 power clip.
If your layout is going to be DCC Digital controlled either now or as a future upgrade then you need to use the R8241 or R8242 power connecting products.
TIP: As a newbie poster on the forum, just be aware that the 'Blue Button with the White Arrow' is not a 'Reply to this post' button. If you want to reply to any of the posts, scroll down and write your reply in the reply text box at the bottom of the page and click the Green 'Reply' button.
See also – further TIPs on how to get the best user experience from this forum.