A gas turbine combustion liner having a novel and improved system for receiving a peripheral device through a floating collar is disclosed. The retaining collar assembly provides planar movement for receiving the peripheral device while preventing the floating collar from rotational movement through an anti-rotation tab on the collar and a collar cap, resulting in reduced wear to the peripheral device. The collar cap can include different configurations for reducing any vibratory effects caused by an oncoming airflow directly contacting the floating collar.