The AdRoll Pixel is uniquely generated when you create an AdRoll account. The AdRoll ID has two components: the Advertiser ID or adroll_adv_id (X) and Pixel ID or adroll_pix_id (Y) for the AdRoll Pixel. To use the AdRoll Pixel, merge the two components together, separating them by a slash (/).
e.g. adroll_adv_id/adroll_pix_id