These are 6-32 Heavy Duty Ball Links from Dubro
Features:
Nylon construction w/brass balls and spacers
Includes:
Two ball links w/pre-inserted balls 1-1/16″ long (end to end)
Two 5/8″ x 6-32 cap head screws
Two 6-32 nylon lock nuts
Two tapered brass spacers (0.142″x 0.252″x0.123″) ID x OD x thickness
Requires:
A 5/16″ wrench for lock nuts
A 3/32″ allen wrench for cap head screws