Photo does not necessarily indicate quantity included. Please read description to see exactly what is included.
The Duraflex Roller Clamp Lock Nut is a replacement part. (It is included with item DF-533.)
The Duraflex Roller Clamp Lock Nut works in conjunction with the Roller Clamp Stud to hold the Duraflex Roller Clamp (DF-521) in place. (Sold per each.)