The Yakima SightLine Towers 4-pack attaches your base rack system to vehicles with flush-mount factory side rails. Its low-profile design is strong, quiet, and aerodynamic and is complete with a matte finish to match modern vehicle styles. Compatible with Yakima crossbars, the SightLine Towers 4-pack uses SightClips for a secure attachment to side rails. For a complete setup, SightClips and crossbars are required, both of which are sold separately.