These are 2-56 Safety Lock Kwik-Link Clevis' from Dubro.
Used on model aircraft for connecting control rods to control surfaces.

FEATURES
Self tapping design leaves no slop on the pushrod threads.
Square nylon shank for easy installation and adjustment.
10% lighter than a steel clevis.
Brass plated stepped steel pin does not bind on control horns and
has a large flat head for easy removal.
Brass plated steel safety lock slides into a groove on the pin for a
secure and solid lock.
Safety lock is mounted in a track system on the clevis body to help
prevent it from being lost.

INCLUDES
Two 2-56 Safety Lock Kwik-Link Clevis'

REQUIREMENTS
2-56 Pushrods of modeler's choice
Installing clevis' onto pushrods

SPECIFICATIONS 
Length: 1-1/8"
Width: 5/16"
Shank Width: 3/16"

COMMENTS 
For other sizes of safety lock clevis', use:
For replacement Slide Locks, order DUBR0821
2-56 (DUBQ1510 qty 2) (DUBQ1511 qty 12)
4-40 (DUBQ1514 qty 2) (DUBQ1515 qty 12)
2mm (DUBQ1518 qty 2) (DUBQ1519 qty 12)