Here they are, a High Quality Jam Nut for a fair price, Cadmium Plated, Left Hand Thread, sold each

7/8 Jam Nut
Hex Nut
Zinc Plated
Thin Nut Low Profile

WARNING: This product can expose you to chemicals including lead, which is known to the State of California to cause cancer. For more information, go to www.P65Warnings.ca.gov