Purpose: The purpose of this article is to study 1-year results of Zenith branch iliac endovascular graft (ZBIS) with the off-label use of a 13 mm spiral Z limb to connect to the aortic main body. Materials and Methods: A retrospective review from 2015 to 2019 of all iliac branch devices (IBDs) was performed at 1 institution that were connected to an aortic main body with a 13 mm spiral Z limb and had at least 1-year follow-up with computed tomography (CT). Primary endpoints are freedom from ZBIS separation from the connection limb, endoleak (EL), or reintervention at 1 year. Secondary endpoints are primary and secondary ZBIS patency, presence of any EL, and aortic reinterventions. Results: Of 149 IBDs implanted in this period, 45 ZBIS in 35 patients were connected with a 13 mm limb and had a 1-year CT; 97% of patients had common iliac artery (CIA) aneurysms, 7% of patients had hypogastric artery (HA) aneurysms, and 30% of patients had bilateral ZBIS implantation. Technical success was 98%. In 84% of cases, the Advanta V12 was used as the HA mating stent; 56% of patients had an EL, mostly type II, which resolved spontaneously in 70% at 1 year, and 9% of ZBIS required reinterventions at 1 year (2 for thrombosis, 2 for type Ic EL from HA mating stent). One-year ZBIS primary patency and secondary patency were 96% and 100%, respectively. No EL was noted to be related to the 13 mm connection limb. No migration or separation of the devices occurred. Conclusions: The use of 13 mm spiral Z limb to connect a ZBIS with the main body in our series yields a high technical success rate and good 12-month outcomes without device separation or migration.