The crescent locking nut accessory measures at 0.75 inch diameter. For use with mounting system to lock precise position and orientation of fixture. Crescent shape allows for easy installation with wrench, allowing you to lock the fixture in place when mounting to a gutter mount, extension stem, or stake. Compatible with our SL01, SL04, SL07, SL07B, SL07P, and SL11. 

Note: SL21, SL23, SL24, SL31 and SL33 all come standard with a crescent locking nut.