The L.O.C.K.™ (Locking 'O' Ring Compression Knuckle) is an industry-leading design that was awarded a patent (US6161948 A) because of its unique mechanical taper-lock, which allows a full 180° vertical adjustment without the use of serrated teeth, which inherently limits aiming.

The L.O.C.K.™ utilizes a high temperature, silicone 'O' Ring providing a water-tight seal. The compressive resistances between the two parts maintain the luminaire's position. The lock screw becomes static eliminating vibration that would normally loosen fastening hardware on other designs. The L.O.C.K.™ is threaded to mate with ½" pipe threads.

The second type of taper lock knuckle builds upon the standard L.O.C.K.™ with the 360SL™. The 360SL™ Mounting System shares the same taper lock design as the former but provides the ability to rotate and tilt the fixture without the need to remove the canopy to loosen a lock nut. The 360SL™ is an upgrade option on many floodlights that include but not limited to Denali Series™, Nite Star™, Delta Star™, McKinley Series™, Rainier Series™ and the Rushmore Series™.

The third type of taper lock knuckle is the patented heavy duty 360HD™ which includes not only the L.O.C.K.™ but also full horizontal and rotational aiming. The 360HD™ is for use with large floodlight products such as the Alps Series™, Yosemite Series™, Sierra Series™, K2 Series™, Lassen Series™ and more.

The last knuckle, is commonly referred to as the ArtiStar™ knuckle. Utilizing the horizontal and rotational aiming of the 360HD™, the ArtiStar™ knuckle with it's robust profile, provides mechanical strength far beyond that of any cast knuckle, which ensures that the ArtiStar™ knuckle is the strongest part of the lighting fixture — not the weakest!