The XR100-BOSS-01-M1 BOSS™ (Bonded Structural Splice) provides a truly seamless, hidden connection for XR-100 Rails. The built-in bonding springs have teeth that bite inside the rail, creating a bonded rail connection that meets all UL standards without any extra tools or hardware. In addition, the BOSS™ eliminates installation restrictions around splice locations by allowing you to place it anywhere along the span, except the outside cantilever.