The system utilizes a C-Shaped Drift Rail and distinctively designed Drift Rail Clip that rotates into position for easy installation. The multifaceted Drift Rail Clips use FastClip Deflection Screws for attachment to the wall studs and allows for 3" vertical deflection (1-1/2" up and down) and is also designed with 1/8" holes to rigidly attach wall studs. To restrict clip lateral movement (drift) along the Drift Rail, install one of the two optional drift stop locking clips (DRLA or DRLC).